Characidae, one of the most diverse families of Characiformes and one of the largest clades of fishes in the world, has a complex taxonomic background, with one issue being the placement of various genera, including Gymnocorymbus. Herein, we generate the first molecular phylogeny for the genus using three nuclear and two mitochondrial loci and review the systematics of Gymnocorymbus. This genus includes the black tetra, a well-known and popular species among aquarists. Molecular phylogeny strongly supports the monophyly of Gymnocorymbus, with this hypothesis corroborated by the presence of three morphological synapomorphies. Of the six previously known nominal species of Gymnocorymbus, three are considered valid herein: Gymnocorymbus bondi from the Río Orinoco basin, Gymnocorymbus ternetzi from the Rio Paraguay basin, and Gymnocorymbus thayeri from the Corantijn and Amazon basin and rivers of northeastern Brazil. A fourth species, Gymnocorymbus flaviolimai sp. n., is described from the Rio Madeira, Amazon basin. Lectotypes are designated for G. ternetzi and G. thayeri. Our results support previous hypotheses of the alignment of Gymnocorymbus close to the subfamily Stethaprioninae and also support the sister relationship between G. ternetzi and G. thayeri, and of that clade as sister to G. bondi. PMID:26248902

Astyanax guianensis is redescribed based on the holotype, paratypes, and additional specimens from the rio Essequibo in Guyana, rio Orinoco in Venezuela and from several localities in the Amazon river basin in Brazil, Colombia and Bolivia. Astyanax guianensis is diagnosed by having five to 10 maxillary teeth, 31 to 35 pored lateral-line scales, 21 to 25 branched anal-fin rays, and a dark vertical humeral blotch followed by a clear area and then by a dark longitudinal stripe, ending before the caudal-fin rays. In addition, comments on the importance of revisionary studies on the species of the Characidae are provided. PMID:25781846

A new species of Moenkhausia is described from Rio Xingu and Rio Tapajós basins, Brazil. The new species is distinguished from its congeners, except from Moenkhausia moisae, by having more scales in the lateral series, 43-47 (v. 23-41 in the remaining congeners). The new species is distinguished from M. moisae by its colour pattern, which consists of a dark midlateral stripe, and an asymmetrical caudal blotch (inconspicuous or faded in specimens from the Rio Arinos) continuous with the midlateral stripe (v. narrow dark midlateral line and conspicuous, regularly rounded and symmetrical blotch not continuous with the midlateral line). The new species is putatively assumed to be mimetic to Jupiaba apenima, in the Rio Xingu and Rio Teles Pires drainages, and to Jupiaba yarina in the Rio Arinos. The two species of Jupiaba are sympatric and remarkably similar in size, general external morphology and colouration to the new species. A small difference occurs in the colouration between the two species of Jupiaba and is also observed in the two respectively sympatric morphotypes of the new species of Moenkhausia. The occurrence of polymorphic Batesian mimicry is therefore discussed for neotropical freshwater fishes. PMID:20738511

We have launched an investigation for Embryonic Development, Larvae and Juvenile Morphology, of Buenos aires tetra in order to build basic data of Characidae and fish seeding production. We brought 50 couples of Characidae from Bizidduck aquarium in Yeosu-si, Jeollanamdo, from Korea on March of 2015. We put them in the tetragonal glass aquarium (50×50×30 cm). Breeding water temperature was 27.5~28.5°C (mean 28.0±0.05°C) and being maintained. The shape of fertilized egg was round shape, and it was adhesive demersal egg. The egg size was 0.63~0.91 mm (mean 0.74±0.07 mm, n=20). After getting fertilized egg, the developmental stage was gastrula stage, and embryo covered almost two-thirds of Yolk. Incubation was happened after 16 hours 13 minutes from gastrula stage, and the tail of juvenile came out first with tearing egg capsule. Immediately after the incubation, prelarvae had 3.78~3.88 mm length (mean 3.84±0.04 mm, n=5), and it had no mouth and anus yet. 34 days after hatching from the incubation, juvenile had 8.63~13.1 mm (mean 10.9±1.66 mm), and it had similar silver-colored body shape with its mother. PMID:25949207

Frugivory and seed dispersal have been poorly studied in Neotropical freshwater fishes. We studied frugivory and seed dispersal by the piraputanga fish ( Brycon hilarii, Characidae) in the Formoso River, Bonito, western Brazil. We examined the stomach contents of 87 fish and found the diet of piraputanga consisted of 24% animal prey (arthropods, snails, and vertebrates), 31% seeds/fruits and 45% other plant material (algae/macrophytes/leaves/flowers). The piraputangas fed on 12 fruit species, and were considered as seed dispersers of eight species. Fruits with soft seeds larger than 10 mm were triturated, but all species with small seeds (e.g. Ficus, Psidium) and one species with large hard seed ( Chrysophyllum gonocarpum) were dispersed. Piraputangas eat more fruits in the dry season just before the migration, but not during the spawning season. Fish length had a positive relation with the presence of fruits in their guts. The gallery forest of the Formoso River apparently does not have any plant species that depend exclusively on B. hilarii for seed dispersal because all fruit species are also dispersed by birds and mammals. Based on seed size and husk hardness of the riparian plant community of Formoso River, however, the piraputangas may potentially disperse at least 50% of the riparian fleshy fruit species and may be particularly important for long-distance dispersal. Therefore, overfishing or other anthropogenic disturbances to the populations of piraputanga may have negative consequences for the riparian forests in this region.

Background With nearly 1,100 species, the fish family Characidae represents more than half of the species of Characiformes, and is a key component of Neotropical freshwater ecosystems. The composition, phylogeny, and classification of Characidae is currently uncertain, despite significant efforts based on analysis of morphological and molecular data. No consensus about the monophyly of this group or its position within the order Characiformes has been reached, challenged by the fact that many key studies to date have non-overlapping taxonomic representation and focus only on subsets of this diversity. Results In the present study we propose a new definition of the family Characidae and a hypothesis of relationships for the Characiformes based on phylogenetic analysis of DNA sequences of two mitochondrial and three nuclear genes (4,680 base pairs). The sequences were obtained from 211 samples representing 166 genera distributed among all 18 recognized families in the order Characiformes, all 14 recognized subfamilies in the Characidae, plus 56 of the genera so far considered incertae sedis in the Characidae. The phylogeny obtained is robust, with most lineages significantly supported by posterior probabilities in Bayesian analysis, and high bootstrap values from maximum likelihood and parsimony analyses. Conclusion A monophyletic assemblage strongly supported in all our phylogenetic analysis is herein defined as the Characidae and includes the characiform species lacking a supraorbital bone and with a derived position of the emergence of the hyoid artery from the anterior ceratohyal. To recognize this and several other monophyletic groups within characiforms we propose changes in the limits of several families to facilitate future studies in the Characiformes and particularly the Characidae. This work presents a new phylogenetic framework for a speciose and morphologically diverse group of freshwater fishes of significant ecological and evolutionary importance

Erythrocharax altipinnis is described from the Serra do Cachimbo, Pará, Brazil. The new taxon is distinguished from all of the Characidae genera by having the pelvic bones firmly attached through the isquiatic processes; a nearly triangular hiatus in the musculature covering the anterior chamber of the swim bladder between the first and second pleural ribs (pseudotympanum); the pedunculate, notably expanded and distally compressed teeth in both jaws; circumorbital series represented by antorbital and four infraorbital bones with laterosensory canals not enclosed; a single tooth row in the premaxillary with the teeth perfectly aligned and similar in shape and cusp number; the first three branched dorsal-fin rays distinctly elongate in males; a bright red adipose and caudal fins in life; a conspicuous dark midlateral stripe extending from the opercle to the tip of the median caudal-fin rays; and by the absence of a humeral spot. The phylogenetic position of the new taxon is discussed using morphological and molecular datasets, with conflicting results of both approaches discussed. Additionally, a summarized discussion on the current problems in the Characidae taxonomy is presented and the principal biases in the morphological dataset are also discussed. PMID:23300963

A new species of Characidae, Moenkhausia celibela, is described from the Rio Amazonas at Santarém, Rio Maraú, several localities in the Rio Tapajós, Rio Curuá-Una, Rio Xingu and Rio Jari, all from the Amazon basin, Brazil. The new species is distinguished from its congeners, except species included in Géry's 1992 Moenkhausia lepidura group, by presenting a dark blotch on the upper caudal-fin lobe, and the lower lobe is hyaline or light grey. Moenkhausia celibela is distinguished from the species of the M. lepidura group by the absence of a humeral spot and the presence of a roughly triangular and dark spot at the caudal-fin base, extending posteriorly along the middle caudal-fin rays, and distinctly separate from the spot on the upper caudal-fin lobe. PMID:20840617

In the 1960s, as a part of the construction of the Furnas Hydroelectric Power Dam, Minas Gerais, Brazil, the Rio Piumhi was diverted from the Rio Grande drainage to the São Francisco River basin, with the resulting introduction of species from one basin to the other. Chromosomal characteristics of various populations of Astyanax fasciatus sensu Eigenmann from the transect region were studied using cytogenetic techniques, with the goal to identify and map the dispersal of invasive species in the Rio São Francisco. Populations of the Rio Grande and Rio Piumhi are distinct from those of the São Francisco basin based on chromosome markers associated to the heterochromatin, Ag-NORs, 18S rDNA, 5S rDNA, and As-51 satellite DNA sites. Individuals with karyomorph originally present in the Piumhi drainage are now present in the São Francisco basin, downstream from the transposition channel. This expansion of the distribution corroborates a hypothesis of progressive substitution of native populations by the invasive Piumhi form. PMID:19641999

Tetragonopterinae encompasses characid species of the genus Tetragonopterus, which are widely distributed throughout east of the Andes in South America. While taxonomy has recently clarified the species diversity and molecular evidence strongly supports the monophyly of Tetragonopterus, no interspecific relationship studies are currently available. Here we used a large molecular dataset composed of two mitochondrial and three nuclear loci containing an extensive taxon sampling within the family Characidae and included eleven species of Tetragonopterus to generate the first time-calibrated phylogeny for Tetragonopterinae. Our results support monophyly of the subfamily represented solely by Tetragonopterus and corroborate previous molecular hypothesis of close relationship with Exodon plus Roeboexodon and the subfamily Characinae. Internally, we found Moenkhausia georgiae as sister species to all remaining species followed by T. rarus, being both species endemic to the Guiana Shield drainages. Species-level relationships are first hypothesized and putative morphological apomorphies are discussed as support to monophyletic clades. Our time-calibrated phylogeny suggested an origin of the genus during the Late Oligocene-Early Miocene. We hypothesized that the Andean geological activity followed by transformations in the Amazonian hydrographic scenario during the Miocene may have promoted most of the lineage diversification within the Tetragonopterus. PMID:26541240

Abstract B chromosomes are dispensable genomic elements found in different groups of animals and plants. In the present study, a whole chromosome probe was generated from a specific heterochromatic B chromosome occurring in cells of the characidae fish Moenkhausia sanctaefilomenae (Steindachner, 1907). The chromosome painting probes were used in fluorescence in situ hybridization (FISH) experiments for the assessment of metaphase chromosomes obtained from individuals from three populations of Moenkhausia sanctaefilomenae. The results revealed that DNA sequences were shared between a specific B chromosome and many chromosomes of the A complement in all populations analyzed, suggesting a possible intra-specific origin of these B chromosomes. However, no hybridization signals were observed in other B chromosomes found in the same individuals, implying a possible independent origin of B chromosome variants in this species. FISH experiments using 18S rDNA probes revealed the presence of non-active ribosomal genes in some B chromosomes and in some chromosomes of the A complement, suggesting that at least two types of B chromosomes had an independent origin. The role of heterochromatic segments and ribosomal sequences in the origin of B chromosomes were discussed. PMID:26753081

This study shows for the first time the presence of a jelly coat on oocytes of neotropical Characiformes fish. This structure could be responsible for the adhesiveness of Astyanax bimaculatus oocytes, a species widely distributed in South America including in the São Francisco River basin in Brazil. Adult specimens of A. bimaculatus were submitted to artificial reproduction in order to analyse the egg morphology and embryonic development. The eggs were fertilised and kept in incubators with a water temperature of 24°C so that embryogenesis could be monitored. Ovulated and unfertilised oocytes were also collected and submitted to routine histological techniques. Astyanax bimaculatus oocytes were found to be spherical, yellowish, and covered by a thin jelly coat with a slightly adhesive surface. The mean oocyte diameter was 1.03 ± 0.03 mm, the perivitelline space was 0.21 ± 0.02 mm and the jelly coat's thickness was 0.04 ± 0.01 mm. Positive periodic acid-Schiff (PAS) stain and Alcian blue stain pH 2.5 indicated the presence of neutral glycoproteins, and carboxylated acid glycoconjugates on the jelly coat that formed mucosubstances that may be associated with egg adhesiveness. At a water temperature of 24°C, blastopore closure and hatching occurred at 5 h and 17 h after fertilisation, respectively. The results of this study provide essential information for phylogenetic studies and for a better understanding of the reproductive strategy of A. bimaculatus, currently included in the incertae sedis group of the Characidae family due to the lack of monophyly among the families of the group. PMID:22717095

The group Incertae sedis within the Characidae family currently includes 88 genera, previously included in the subfamily Tetragonopterinae. Among them is the genus Astyanax comprising a group of species with similar morphology and widely distributed in the Neotropics. Thus, the present study aimed to analyze the karyotype diversity in Astyanax species from different watersheds by conventional Giemsa staining, C-banding and fluorescence in situ hybridization (FISH rDNA 18S) probe.specimens of Astyanax aff. paranae belonging to the "scabripinnis complex", Astyanax asunsionensis and Astyanax aff. bimaculatus were analyzed". Two sympatric karyomorphs were observed in Astyanax.aff paranae, one of them having2n=48andthe other one with 2n=50 chromosomes. Other population of this same species also presented 2n=50 chromosomes, but differing in the karyotype formula and with macro supernumerary chromosome found in 100% of the cells in about 80%of females analyzed. Two population of A. asuncionensis and one population of Astyanax. aff. bimaculatus, also showed a diploid number of 50 chromosomes, but also differing in their karyotype formulas. Therefore, A. asuncionensis was also characterized by intraspecific chromosome diversity. The C-banding analysis was able to demonstrate a distinctable to demonstrate a distinct pattern of heterochromatin differing A. asuncionensis from Astyanax aff. paranae and Astyanax aff. bimaculatus. The supernumerary chromosome of Astyanax aff. paranae proved completely heterochromatic. Only Astyanax.aff. bimaculatus multiple showed multiple sites of nucleolar organizing regions. The other species were characterized by having a simple system of NOR. These data contributes to the know ledge of the existing biodiversity in our fish fauna, here highlighted by the inter- and intraspecific chromosomal diversity in the genus Astyanax. PMID:26934153

A new nematode species, Philometra nattereri n. sp. (Philometridae), is described from female specimens found in the oculo-orbits and nasal cavity of the red piranha Pygocentrus nattereri Kner (Characiformes: Characidae) from five lakes in Central Amazonia, Brazil, collected in 2008 and 2009 (overall prevalence 12%, intensity 1-3 nematodes per fish). Based on light and scanning electron microscopical examination, the new species differs from most other congeners parasitising freshwater fishes in that its oesophageal gland extends anteriorly far anterior to the level of the nerve-ring, in the presence of 14 small cephalic papillae arranged in two circles and in having two minute caudal projections. This is the first species of Philometra Costa, 1845 reported from fishes of the family Characidae and the second valid species of this genus parasitic in freshwater fishes of Brazil and South America. PMID:22983801

Nutrient recycling by animals is a potentially important biogeochemical process in both terrestrial and aquatic ecosystems. Stoichiometric traits of individual species may result in some taxa playing disproportionately important roles in the recycling of nutrients relative to their biomass, acting as keystone nutrient recyclers. We examined factors controlling the relative contribution of 12 Neotropical fish species to nutrient recycling in four streams spanning a range of phosphorus (P) levels. In high-P conditions (135 ??g/L soluble reactive phosphorus, SRP), most species fed on P-enriched diets and P excretion rates were high across species. In low-P conditions (3 ??g/L SRP), aquatic food resources were depleted in P, and species with higher body P content showed low rates of P recycling. However, fishes that were subsidized by terrestrial inputs were decoupled from aquatic P availability and therefore excreted P at disproportionately high rates. One of these species, Astyanax aeneus (Characidae), represented 12% of the total population and 18% of the total biomass of the fish assemblage in our focal low-P study stream but had P excretion rates >10-fold higher than other abundant fishes. As a result, we estimated that P excretion by A. aeneus accounted for 90% of the P recycled by this fish assemblage and also supplied ???90% of the stream P demand in this P-limited ecosystem. Nitrogen excretion rates showed little variation among species, and the contribution of a given species to ecosystem N recycling was largely dependent upon the total biomass of that species. Because of the high variability in P excretion rates among fish species, ecosystem-level P recycling could be particularly sensitive to changes in fish community structure in P-limited systems. ?? 2011 by the Ecological Society of America.

Anacanthorus franciscanus sp. n. and Anacanthorus brevicirrus sp. n. (Dactylogyridae) are described from the gills of the matrinchã, Brycon orthotaenia Günther (Characidae), from the Rio São Francisco in Brazil. Anacanthorusfranciscanus most closely resembles Anacanthorus e[egans and A. kruidenieri from the matrinchõ, Brycon melanopterus, of the Amazon River Basin. It differs from these species in part by having the bulbous proximal end of the hook shank with two translucent regions. Anacanthorus brevicirrus resembles A. franciscanus, A. kruidenieri and A. elegans but is differentiated from these species by its short straight male copulatory organ and by having one translucent region in the bulbous base of the hook shank. PMID:20941907

The life cycle of Neocladocystis intestinalis (Vaz, 1932) was resolved experimentally. The prosobranchiate snail Aylacostoma chloroticum Hylton Scott (Thiaridae) collected in the Yacyretá Dam, Province of Misiones, Argentina, was found naturally infected with cercariae that possessed pigmented eye spots, 7 pairs of penetration glands, 12 pairs of flame cells, and a V-shaped, or Y-shaped excretory vesicle with very short stem. The cercariae developed in oval cysts, which were found on fin rays, and under scales of naturally and experimentally exposed tetragonopterid fish species and of experimentally exposed poecilid and prochilodont fish species. Adults were obtained experimentally from juvenile Salminus brasiliensis (Characidae), bred in captivity, and infected with metacercariae from albino Gymnocorymbus ternetzi (Tetragonopteridae), which had been exposed to emerging cercariae. PMID:26984207

Five new species of the Neotropical characiform genus Astyanax Baird & Girard are described from Rio Iguaçu at the border of Paraná and Santa Catarina states, southeastern Brazil and Astyanax gymnogenis Eigenmann is redescribed. Each new species can be distinguished from all other Astyanax species from the upper Rio Paraná basin by exclusive combinations of: tooth shape, number of dental cuspids, distance between third infraorbital and preopercle, number of lateral line scales, longitudinal series of scales, number of gill-rakers and differences from shape of body and head traits. This study proposes the species of genus Astyanax from Rio Iguaçu as probably endemic, since all of them are absent from tributaries of the Rio Paraná hydrographic system. The high degree of diversification acquired by those Astyanax species in the Iguaçu basin may perhaps be allied to the long isolation period of this river from the Rio Paraná basin caused by the Iguaçu waterfalls. This barrier probably isolated those basins resulting in original groups of Characiformes and then Astyanax species, both isolated from one another and both different from their relatives in neighbouring basins. PMID:21085790

Karyotypic features of Rhoadsiaaltipinna Fowler, 1911 from Ecuador were investigated by examining metaphase chromosomes through Giemsa staining, C-banding, Ag-NOR, and two-color-fluorescence in situ hybridization (FISH) for mapping of 18S and 5S ribosomal genes. The species exhibit a karyotype with 2n = 50, composed of 10 metacentric, 26 submetacentric and 14 subtelocentric elements, with a fundamental number FN=86 and is characterized by the presence of a larger metacentric pair (number 1), which is about 2/3 longer than the average length of the rest of the metacentric series. Sex chromosomes were not observed. Heterochromatin is identifiable on 44 chromosomes, distributed in paracentromeric position near the centromere. The first metacentric pair presents two well-defined heterochromatic blocks in paracentromeric position, near the centromere. Impregnation with silver nitrate showed a single pair of Ag-positive NORs localized at terminal regions of the short arms of the subtelocentric chromosome pair number 12. FISH assay confirmed these localization of NORs and revealed that minor rDNA clusters occur interstitially on the larger metacentric pair number 1. Comparison of results here reported with those available on other Characidae permit to hypothesize that the presence of a very large metacentric pair might represent a unique and derived condition that characterize one of four major lineages molecularly identified in this family. PMID:26140168

Abstract Karyotypic features of Rhoadsia altipinna Fowler, 1911 from Ecuador were investigated by examining metaphase chromosomes through Giemsa staining, C-banding, Ag-NOR, and two-color-fluorescence in situ hybridization (FISH) for mapping of 18S and 5S ribosomal genes. The species exhibit a karyotype with 2n = 50, composed of 10 metacentric, 26 submetacentric and 14 subtelocentric elements, with a fundamental number FN=86 and is characterized by the presence of a larger metacentric pair (number 1), which is about 2/3 longer than the average length of the rest of the metacentric series. Sex chromosomes were not observed. Heterochromatin is identifiable on 44 chromosomes, distributed in paracentromeric position near the centromere. The first metacentric pair presents two well-defined heterochromatic blocks in paracentromeric position, near the centromere. Impregnation with silver nitrate showed a single pair of Ag-positive NORs localized at terminal regions of the short arms of the subtelocentric chromosome pair number 12. FISH assay confirmed these localization of NORs and revealed that minor rDNA clusters occur interstitially on the larger metacentric pair number 1. Comparison of results here reported with those available on other Characidae permit to hypothesize that the presence of a very large metacentric pair might represent a unique and derived condition that characterize one of four major lineages molecularly identified in this family. PMID:26140168

During the 1988 rainy season, I studied the 24 h feeding chronology of juvenile (40–68 mm standard length) piranhas, Pygocentrus notatus (Characidae: Serrasalminae) from a natural population inhabiting a small savanna stream in Apure State, Venezuela. Stomach contents analyses, supported by laboratory determinations of digestion rate, showed that these fish are primarily diurnal carnivores. Predatory activity on 4–5 August 1988 increased markedly after sunrise, peaked around 1100 h, and essentially stopped after sunset. Means of stomach content weight-to-fish weight ratios among the periods sampled were significantly different. Small fish were the major prey at all hours (81% of total prey volume). Underlying factors responsible for the observed 24 h feeding patterns were not investigated, but avoidance of predation by adult piranhas, which were very active near sunset, may have been important.

Astyanax is a genus of Characidae fishes currently composed of 155 valid species. Previous cytogenetic studies revealed high chromosomal diversification among them, and several studies have been performed using traditional cytogenetic techniques to investigate karyotypes and chromosomal locations of 18S and 5S rDNA genes. However, only a few studies are currently available about other repetitive sequences. Here, the chromosomal location of small nuclear RNA genes, identified as U1 and U2 snRNA clusters, was established and compared to the distribution of 5S rDNA and histone clusters in 5 Astyanax species (A. paranae, A. fasciatus, A. bockmanni, A. altiparanae, and A. jordani) using FISH. The cytogenetic mapping of U1 and U2 snRNA demonstrated a conserved pattern in the number of sites per genome independent of the location in Astyanax species. The location of the U1 snRNA gene was frequently associated with 5S rDNA sequences, indicating a possible interaction between the distinct repetitive DNA families. Finally, comparisons involving the location of U1 and U2 snRNA clusters in the chromosomes of Astyanax species revealed a very diverse pattern, suggesting that many rearrangements have occurred during the diversification process of this group. PMID:26329975

Allozyme electrophoresis was used to examine 12 enzymatic systems in two populations of the genus Neoplecostomus from the Paraná River basin. Samples of Neoplecostomus sp. 1 were collected in Paraitinguinha stream of the Tietê River basin, in the municipality of Salesópolis, São Paulo State, and those of Neoplecostomus sp. 2 from São Domingos stream of the Rio Grande River basin, in the municipality of Muzambinho, Minas Gerais State. The genetic variability of the two populations was estimated by Nei's expected heterozygosity and was considered lower than average for populations of freshwater fish. The proportion of polymorphic loci was low (only 5.26% for the locus Idh). The low frequency of heterozygosity for both populations revealed a high fixation of alleles for each locus. Homozygote excess was observed in both populations. The values of Nei's genetic identity and the presence of loci with different allele frequencies in both populations may imply that the two populations belong to different species. The genetic variability between populations was compared to other data for loricariids. PMID:21931525

Allozyme electrophoresis was used to examine 12 enzymatic systems in two populations of the genus Neoplecostomus from the Paraná River basin. Samples of Neoplecostomus sp. 1 were collected in Paraitinguinha stream of the Tietê River basin, in the municipality of Salesópolis, São Paulo State, and those of Neoplecostomus sp. 2 from São Domingos stream of the Rio Grande River basin, in the municipality of Muzambinho, Minas Gerais State. The genetic variability of the two populations was estimated by Nei’s expected heterozygosity and was considered lower than average for populations of freshwater fish. The proportion of polymorphic loci was low (only 5.26% for the locus Idh). The low frequency of heterozygosity for both populations revealed a high fixation of alleles for each locus. Homozygote excess was observed in both populations. The values of Nei’s genetic identity and the presence of loci with different allele frequencies in both populations may imply that the two populations belong to different species. The genetic variability between populations was compared to other data for loricariids. PMID:21931525

Abstract Two new species of Hisonotus are described from the rio Paraná-Paraguay basin in Brazil. The most remarkable features of the new species are the odontodes forming longitudinally aligned rows (one odontode after the other, but not necessarily forming parallel series) on the head and trunk (vs. odontodes not forming longitudinally aligned rows), a pair of rostral plates at the tip of the snout (vs. a single rostral plate), the functional v-shaped spinelet (vs. spinelet non-functional, square-shaped, or absent). These features suggest close phylogenetic relationships with Hisonotus bockmanni, H. insperatus, H. luteofrenatus and H. piracanjuba. Additionally, both new species are distinguished from their congeners by characters related to head length and depth, orbital diameter, suborbital depth, caudal peduncle depth, pectoral-fin spine length, snout length and counts of teeth. Hisonotus paresi sp. n. further differs from its congeners by having contrasting dark geometric spots on the anterodorsal region of the body, a character lacking in H. oliveirai sp. n. The variation in number and shape of the rostral plate, posterior rostrum plates, infraorbitals and the preopercle in both new species and in H. insperatus are discussed. PMID:24715789

Brycon orthotaenia is an important fish for commercial and sport fishing and may reach 7 kg in body weight; it is endangered in some regions of Brazil's São Francisco River Basin. Breeders were subjected to spawning induction to analyse the early development; oocytes and semen were obtained by manual extrusion and fertilization was carried out using the dry method. After fertilization, eggs were kept in incubators at 24°C. Egg samples were collected every 10 min until hatching in order to monitor embryonic development and were analysed and photographed. Larvae samples were collected daily until the seventh day to analyse the larvae development; larvae were fixed in Bouin's fluid and subjected to routine histological and histochemical techniques for glycoprotein and glyco-conjugated detection. Oocyte extrusion occurred 6 h after the second hormone dose at 26°C. The recently extruded oocytes were spherical, dark green and non-adhesive, with a diameter of 1479.67 ± 53.18 and 3094.60 ± 80.34 μm after hydration. The blastopore closure occurred within 7 h 30 min of fertilization and the fertilization rate was 50.0 ± 5.5 % at 24°C. Embryonic development was completed within 21 h 30 min of fertilization. Complete yolk sac resorption and mouth opening occurred on the third day after hatching, at which time an adhesive organ with mucosubstances was observed. On the third day, an olfactory chamber with cilia and intense cannibalism amongst the larvae was observed. The complete differentiation of the digestive system occurred on the fifth day and the nervous and sensorial systems differentiation occurred on the sixth to seventh days. PMID:21733293

The Neotropical catfish genus Tympanopleura, previously synonymized within Ageneiosus, is revalidated and included species are reviewed. Six species are recognized, two of which are described as new. Tympanopleura is distinguished from Ageneiosus by having an enlarged gas bladder not strongly encapsulated in bone; a prominent pseudotympanum consisting of an area on the side of the body devoid of epaxial musculature where the gas bladder contacts the internal coelomic wall; short, blunt head without greatly elongated jaws; and smaller adult body size. Species of Tympanopleura are distinguished from each other on the basis of unique meristic, morphometric, and pigmentation differences. Ageneiosus melanopogon and Tympanopleura nigricollis are junior synonyms ofTympanopleura atronasus. Tympanopleura alta is a junior synonym of Tympanopleura brevis. A lectotype is designated for T. brevis. Ageneiosus madeirensis is a junior synonym of Tympanopleura rondoni. Tympanopleura atronasus, T. brevis, T. longipinna, and T. rondoni are relatively widespread in the middle and upper Amazon River basin. Tympanopleura cryptica is described from relatively few specimens collected in the upper portion of the Amazon River basin in Peru and the middle portion of that basin in Brazil. Tympanopleura piperata is distributed in the upper and middle Amazon River basin, as well as in the Essequibo River drainage of Guyana.

Hyphessobrycon eques is a famous fish for ornamental fish market and aquarium. They are inhabit in regions of Amazon and Paraguay River basin. Serpae fishs were investigated 2-3 males are chased to female, and then males attempted to simulate the females abdomen. After fertilization, eggs were kept in incubators at 28°C. The fertilized eggs had adhesive and demesal characteristics and had a mean diameter of 0.92 ± 0.01 mm. Larvae hatched at 16 hrs post fertilization. The hatched larvae averaged 2.90 ± 0.16 mm in total length (LT ). Complete yolk sac resorption and mouth opening occurred on the third day post hatching. At 45 days post hatching, the larvae were 12.5 ± 1.60 mm LT and had reached the juvenile stage. PMID:25949194

A new species of Farlowella is described from El Carmen de Chucurí in the Departamento de Santander, western flank of the Cordillera Oriental, río Magdalena Basin, Colombia. Farlowella yarigui n. sp. differs from its congeners in lateral body plate morphology, abdominal cover, cephalic hypertrophied odontodes, and details of coloration. This is the first verifiable record of the genus in the Magdalena drainage. Aspects of natural history and implications of this finding are provided concerning the state of knowledge of the fishes of the río Magdalena Basin. Previous records of Farlowella gracilis in the río Cauca basin are examined and herein considered erroneous, rendering the new species the only representative of the genus in the Magdalena-Cauca system. A key to species of Farlowella from Colombia is provided. PMID:24870891

We report the complete mitochondrial genome of the fish Salminus brasiliensis, popularly known as dourado. It is a circular, 17,721 bp long DNA molecule, containing 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and a non-coding Control Region of 2128 bp, a relatively large molecule when compared to other closely related fishes. All protein-coding genes are on the heavy strand, except for Nd6, and all have ATG as the start codon, except for Cox1 gene which has a GTG start codon. Seven protein-coding genes have incomplete stop codons (Nd2, Cox2, Atp6, Nd4, and Cytb have T- -, and Cox3 and Nd3 have TA-). TAG is the stop codon for Nd6 and AGG is the stop codon for Cox1. PMID:25208163

Parodontidae fish show few morphological characteristics for the identification of their representatives and chromosomal analyses have provided reliable features for determining the interrelationships in this family. In this study, the chromosomes of Apareiodon hasemani from the São Francisco River basin, Brazil, were analyzed and showed a karyotype with 2n = 54 meta/submetacentric chromosomes, and a ZZ/ZW sex chromosome system. The study revealed active NORs located on pair 11 and additional 18S rDNA sites on pairs 7 and 22. The 5S rDNA locus was found in pair 14. It showed a pericentric inversion regarding the ancestral condition. The satellite DNA pPh2004 was absent in the chromosomes of A. hasemani, a shared condition with most members of Apareiodon. The WAp probe was able to detect the amplification region of the W chromosome, corroborating the common origin of the system within Parodontidae. These chromosomal data corroborate an origin for the ZW system of Parodontidae and aid in the understanding of the differentiation of sex chromosome systems in Neotropical fishes. PMID:23271937

Tomeurus gracilis is a species long considered pivotal in understanding the evolution of livebearing in atherinomorph fishes. Tomeurus gracilis is a zygoparous or embryoparous poeciliid: internal fertilization is followed by females laying fertilized eggs singly or retaining fertilized eggs until or near hatching. Tomeurus was hypothesized as the sister group of the viviparous poeciliids until it was proposed as a close relative of a derived viviparous poeciliid, Cnesterodon, hence nested among viviparous taxa rather than near the root of the tree. Here, we describe and compare reproductive morphological characters of the little-known Tomeurus with those of representative atherinomorphs. In Tomeurus and Cnesterodon, sperm are packaged in naked sperm bundles, or spermatozeugmata, in a configuration considered here diagnostic of viviparous poeciliids. Testes are single and free sperm are stored in the ovary in both taxa in contrast to oviparous atherinomorphs in which testes are paired and sperm are not packaged and not stored in the ovary. Efferent ducts in Cnesterodon testes and other viviparous poeciliids have a PAS-positive secretion demonstrating presence of a glycoprotein that inactivates sperm or prevents final sperm maturation. No PAS-positive staining secretion was observed in Tomeurus or oviparous atherinomorphs. Tomeurus shares apomorphic reproductive characters, such as sperm bundle and testis morphology and a gonopodium, with viviparous poeciliids and plesiomorphic characters, such as a thick zona pellucida with filaments, with oviparous taxa. We do not postulate loss or reversal of viviparity in Tomeurus, and we corroborate its phylogenetic position as sister to the viviparous poeciliids. PMID:20862693

The freshwater fish Ancistrus brevifilis, which is found in Venezuelan rivers, is considered a potential sentinel fish in ecotoxicological studies. The cadmium (Cd) effect on the mitochondrial viability (MV) and acid soluble thiols levels (AST) in A. brevifilis tissues (liver, kidney, heart, and gill) was evaluated. Forty-two fish with similar sizes and weights were randomly selected, of which 7 fish (with their respective replicate) were exposed for 7 and 30 days to a Cd sublethal concentration (0.1 mg.l(-1)). We determined the MV through a Janus Green B colorimetric assay and we obtained the concentration of AST by Ellman's method. Mitochondrial viability decreased in fish exposed to Cd for 30 days with the liver being the most affected tissue. We also detected a significant decrease in AST levels was in fishes exposed to Cd for 7 days in liver and kidney tissues; these results suggests that AST levels are elevated in some tissues may act as cytoprotective and adaptive alternative mechanism related to the ROS detoxification, maintenance redox status and mitochondrial viability. Organ-specifics variations were observed in both assays. We conclude that the Cd exposure effect on AST levels and MV, vary across fish tissues and is related to the exposure duration, the molecule dynamics in different tissues, the organism and environmental conditions. PMID:26623384

The freshwater fish Ancistrus brevifilis, which is found in Venezuelan rivers, is considered a potential sentinel fish in ecotoxicological studies. The cadmium (Cd) effect on the mitochondrial viability (MV) and acid soluble thiols levels (AST) in A. brevifilis tissues (liver, kidney, heart, and gill) was evaluated. Forty-two fish with similar sizes and weights were randomly selected, of which 7 fish (with their respective replicate) were exposed for 7 and 30 days to a Cd sublethal concentration (0.1 mg.l-1). We determined the MV through a Janus Green B colorimetric assay and we obtained the concentration of AST by Ellman’s method. Mitochondrial viability decreased in fish exposed to Cd for 30 days with the liver being the most affected tissue. We also detected a significant decrease in AST levels was in fishes exposed to Cd for 7 days in liver and kidney tissues; these results suggests that AST levels are elevated in some tissues may act as cytoprotective and adaptive alternative mechanism related to the ROS detoxification, maintenance redox status and mitochondrial viability. Organ-specifics variations were observed in both assays. We conclude that the Cd exposure effect on AST levels and MV, vary across fish tissues and is related to the exposure duration, the molecule dynamics in different tissues, the organism and environmental conditions. PMID:26623384

The visual system of Teleost fishes has a wide range of adaptations. The eye has suffered modifications, mainly towards better sensitivity and visual resolution according to specific environmental conditions. In that way, this organ is so important for survival. In spite of being the most commercialized Orinoquia species, and one of the most important ornamental fish worldwide, there are almost no studies on the communication systems of P. axelrodi (including vision). We studied the eye in ten individuals of P. axelrodi, with a mean total length of 2.7 cm (SD = 0.2, n = 20). We measured eye relative size (TRO) after sacrifice. Heads were processed for hematoxylin-eosin, and 8 microm thick sections were obtained. Images were digitalized for histological identification and morphometrics. The relation between TRO and body length was 9.8% (SD= 1.1, n= 20); lens was spherical with a relative size of 64.3% (SD = 4.9, n = 20). Rete mirabilis choroid was composed mainly by capillaries, while sclera was composed of cartilaginous tissue. Retina with eight layers and two membranes. An areae centrales was observed in the posterior retina. Iris covered by a simple cubic epithelium. Cornea of endotelial tissue with two membranes. Pupil almost circular, with a naso-caudal elongation. Measures of retina thickness were as follows: lateral retina 144.5 microm (SD = 5.4, n = 20), temporal retina 210.4 microm (SD = 14.8, n = 20). Lens measurements were: dorso-ventral 759.6 microm (SD = 31.7, n = 20), antero-posterior 763.4 microm (SD = 30.7, n = 20). Cornea thickness was 27.6 microm (SD = 4.3, n = 20); iris thickness was 18.9 microm (SD = 1.9, n = 20); rete mirabilis choroid 22.2 microm (SD = 3.2, n = 20) and sclera: 15.9 microm (SD = 1.2, n = 20). This species has a typical Teleost eye conformation. The retina was thicker in the posterior area, probably related to the presence of neuron groups. This modification allows for a better sharpness and visual resolution. The TRO, areae centrales in the retina, and thin cornea, suggests the need of a well developed visual system resulting from a predatory diet. PMID:20073338

Eukaryote genomes are frequently burdened with the presence of supernumerary (B) chromosomes. Their origin is frequently investigated by chromosome painting, under the hypothesis that sharing the repetitive DNA sequences contained in the painting probes is a sign of common descent. However, the intragenomic mobility of many anonymous DNA sequences contained in these probes (e.g., transposable elements) adds high uncertainty to this conclusion. Here we test the validity of chromosome painting to investigate B chromosome origin by comparing its results for seven B chromosome types in two fish species genus Astyanax, with those obtained (1) by means of the physical mapping of 18S ribosomal DNA (rDNA), H1 histone genes, the As51 satellite DNA and the (AC)15 microsatellite, and (2) by comparing the nucleotide sequence of one of these families (ITS regions from ribosomal DNA) between genomic DNA from B-lacking individuals in both species and the microdissected DNA from two metacentric B chromosomes found in these same species. Intra- and inter-specific painting suggested that all B chromosomes that were assayed shared homologous DNA sequences among them, as well as with a variable number of A chromosomes in each species. This finding would be consistent with a common origin for all seven B chromosomes analyzed. By contrast, the physical mapping of repetitive DNA sequences failed to give support to this hypothesis, as no more than two B-types shared a given repetitive DNA. Finally, sequence analysis of the ITS regions suggested that at least some of the B chromosomes could have had a common origin. PMID:26984341

Light and electron microscopy were used to investigate the morphology of reproductive characters in a characid fish, Brittanichthys axelrodi. Spermatozoa were found in ovaries of females, thereby confirming insemination in this species. Bony hooks can be found on the fourth unbranched ray and branched rays 1-4 of the anal fin and the unique sigmoidally-curved ray of the caudal fin in mature males. Testes have three distinct regions: an anterior spermatogenic region, an aspermatogenic middle region lined with a simple squamous epithelium and used for storage of mature spermatozoa, and a posterior region of coiled chambers lined with a high simple cuboidal epithelium. The most posterior region appears to be instrumental in the formation and storage of spermatozeugmata, unencapsulated sperm packets. Thus far, this tripartite testis morphology is unique among characids. The mature spermatozoon has an elongate nucleus ( approximately 5 microm in length). A striated rootlet originates at the anterior end of the distal centriole and continues to the anterior tip of the cell. The striated rootlet wraps around the entire ventral area of the anterior part of the nucleus and appears to continue around the anterior tip of the nucleus and down the dorsal side as electron-dense material. Several large, spherical mitochondria ( approximately 0.6 microm in diameter) with lamellar cristae overlap the posterior end of the nucleus and continue beyond together with the cytoplasmic collar that contains the flagellum which lacks axonemal fins. Each spermatozeugma is lanceolate in shape when sectioned mid-sagitally, with the core staining positively for mucopolysaccharides. In both sexes, the gonopore opens posterior to the anus, with the urinary pore having a separate opening posterior to the gonopore. Bands of skeletal muscle were found in the area of the male gonopore. These morphological features are likely linked to the reproductive mode of insemination, a trait that is so far as known, relatively rare among teleost fishes, but is proving increasingly frequent among certain groups of characid fishes. PMID:17146774

Astyanax pirabitira, new species, is described from the upper portion of the rio das Antas, laguna dos Patos system, and from the rio Pelotas, upper rio Uruguay drainage, Rio Grande do Sul State, Brazil. The new species belongs to the A. scabripinnis species complex and differs from its congeners by a combination of characters, viz., body depth (27.1-34.0% of standard length), narrow interorbital width (22.2-28.7% of head length), head depth (72.9-97.0% of HL), number of branched anal-fin rays (15-20), number of lateral line scales (37-40), one or two maxillary teeth, two humeral spots and absence of secondary sexual characters (bony hooks in the fins or other differences in the morphology). Comments on the endemic fish fauna of the region are presented. PMID:26106724

DNA barcoding can be an effective tool for fast and accurate species-level identification based on sequencing of the mitochondrial cytochrome c oxidase subunit (COI) gene. The diversity of this fragment can be used to estimate the richness of the respective species. In this study, we explored the use of DNA barcoding in a group of ornamental freshwater fish of the genus Hyphessobrycon. We sequenced the COI from 10 species of Hyphessobrycon belonging to the “Rosy Tetra Clade” collected from the Amazon and Negro River basins and combined our results with published data. The average conspecific and congeneric Kimura 2-parameter distances were 2.3% and 19.3%, respectively. Six of the 10 species were easily distinguishable by DNA barcoding (H. bentosi, H. copelandi, H. eques, H. epicharis, H. pulchrippinis, and H. sweglesi), whereas the remaining species (H. erythrostigma, H. pyrrhonotus, H. rosaceus and H. socolofi) lacked reciprocal monophyly. Although the COI gene was not fully diagnostic, the discovery of distinct evolutionary units in certain Hyphessobrycon species under the same specific epithet as well as haplotype sharing between different species suggest that DNA barcoding is useful for species identification in this speciose genus. PMID:24878569

In the present study, we describe feeding habits of Deuterodon sp. from the Ubatiba River and explore if diet changes according to a temporal cycle of dry and wet seasons. We observed that Deuterodon sp. fed on an extremely high diversity of items ranging from organic matter, sediment (sand plus quartz parts), algae, seeds and leaves to animal organisms, such as, crustaceans, oligochaets and several life stages of terrestrial and aquatic insects, indicating an omnivorous diet. An important shift in the use of feeding resources was also registered; animal and vegetal items had alternated importance between both seasons. Allochthonous vs. autochthonous items analysis showed predominance of allochthonous items during dry season while no significant differences were registered during wet season. PMID:12914416

We assessed spatial and seasonal changes in the diet of Oligosarcus hepsetus in order to describe the strategy developed by this species that allows their very high abundance in Lajes reservoir, Rio de Janeiro, Brazil. Fish samplings were carried out using gill nets, deployed during ca. 12 and 24 hours, between April 2001 and May 2002. A total of 289 individuals were examined, of which 97 showed gut contents. We used the index of relative importance (IRI) to compare probable dietary shifts, and the frequency of occurrence (% OC) to analyze possible ontogenetic influences on feeding. O. hepsetus showed carnivorous habits, feeding preferably on fish and insects, the latter of which occurred in 71.0% of the guts presenting contents. O. hepsetus consumed different items along the three reservoir zones: insects (61.0% IRI) and Cichla monoculus (38.9% IRI) in the lower zone; Lepidoptera (57.0% IRI) in the middle zone; and C. monoculus (77.0% IRI) in the upper zone. Food items changed seasonally with C. nonloculus predominating in autumn 2001, and Hymenoptera and Lepidoptera in the winter. In spring almost all food was Lepidoptera (99.8% IRI), while in the summer Hemiptera dominated in the diet. In autumn 2002 Hemiptera (97.0% IRI) was dominant, in significant contrast with the previous autumn. Individuals smaller than 190 mm SL fed heavily on insects, while fishes predominated in the diet of individuals larger than 190 mm SL. Shifts in prey-capture ability among length classes suggest decreasing intraspecific competition. A higher food plasticity seems to be the strategy employed by this opportunist species, which used food resources available in the reservoir. PMID:16025897

The reproductive biology of two inseminating Glandulocaudini species, Mimagoniates microlepis and Mimagoniates rheocharis, was investigated and compared with reproductive patterns described for other inseminating and non-inseminating characids, hypothesizing the evolutionary history of these reproductive traits. The long reproductive period, with higher activity in colder months, distinguishes the reproductive strategy of these species when compared with most characiforms. The M. rheocharis population was structured in two groups of males throughout the year, mature males with high gonado-somatic index (IG = 2·0 and 4·4) and immature and maturing males with low IG values (0·0 and 1·2). Mimagoniates rheocharis and M. microlepis showed the lowest absolute mean fecundities known for characids, indicating that inseminating species allocate less energy to oocyte production and reinforcing the hypothesis that insemination has an adaptive advantage, which provides a higher chance of fertilization. PMID:26762286

Histochemical properties of goblet cells in intestine of a stomach-less teleost, tiger barb (Puntius tetrazona), and a stomach-containing teleost, black tetra (Gymnocorymbus ternetzi), are described and compared. The intestine goblet cells were mostly wide in both species, but in tiger barb, some of them were markedly thinner. In black tetra, all the intestine goblet cells displayed magenta colour after PAS, whereas in the tiger barb, only the thinner goblet cells displayed such affinity. The latter cell type was coloured strongly magenta when the tissue was treated with alcian blue (pH 2.5) followed by PAS, whereas the wide goblet cells in tiger barb and all goblet cells in black tetra displayed mainly a blue colour after such treatment. Further, the goblet cells in both species were coloured cleanly blue after high iron diamine followed by alcian blue (pH 2.5). The intestine goblet cells in both species displayed a moderate affinity to WGA and concanavalin A lectins and no affinity to DBA. Most of the goblet cells displayed no affinity to PNA, but some of them in the tiger barb displayed a moderate or strong affinity to this lectin. The affinity to WGA was somewhat strengthened after pre-treatment with neuraminidase. These results suggest that tiger barb contains two types or variants of intestinal goblet cells: high numbers of wide cells filled by acidic, non-sulphated mucin and some thinner cells filled by neutral mucin. The intestine goblet cells in black tetra were filled by variable amounts of neutral and acidic mucin, but the total number of such cells is much less than in tiger barb. The present lectin and neuraminidase results suggest that the intestinal mucins in both species contain significant amounts of N-acetylglucosamine, sialic acid and glucose/mannose, but seem to lack N-acetylgalactosamine. However, some of these cells in tiger barb contain moderate to large amounts of galactose. Together, these results suggest significant species-specific features of the intestine goblet cells and mucin types in tiger barb and black tetra. In conclusion, the present results suggest that the diet and feeding habits in stomach-less teleosts compared with stomach-containing teleosts, greatly influence the number of intestine goblet cells and type of mucin in these cells. PMID:23952769

Fish biodiversity of aquatic ecosystems is highly threatened by different economic activities driven by human populations, and its description is increasingly a priority. For the Cauca-Magdalena River system we have described 14 species, and the purpose of this paper was to describe three new species belonging to the same genus Hemibrycon from the Nare and Guatapé River drainages of the middle Magdalena River, Colombia. The description was based on a series of 200 specimens, and the use of morphometric, meristic and osteological characters, as well as fish distribution and morphogeometric analytical methods. We have found that Hemibrycon fasciatus n. sp. (n = 54) differs from other species of Hemibrycon (that also have a vertical humeral spot) in having: melanophores outlining the posterior margins of the scales along sides of body; humeral spot extending onto posterior margin of opercle; a dark lateral stripe, formed by deep pigment that is continuous with the peduncular spot; the toothed portion of the maxilla not reaching the dorsal margin of the dentary (vs. toothed portion of maxilla extending beyond dorsal margin of dentary); all maxillary teeth tricuspid (vs. some unicuspid teeth present on maxilla). H. cardalensis n. sp. (n = 64) differs in having: a vertically elongate humeral spot that extends one or two scales below the lateral line canal. H. cardalensis n. sp. differs from all congeners in having the pigment of the caudal spot restricted to the ventral half of the caudal peduncle, and in having melanophores around the anterior scales of the lateral line. Hemibrycon antioquiae n. sp. (n = 82) differs in having a circular humeral spot. It differs from the other species with a circular humeral spot, like H. mikrostiktos, in having a projection of disperse melanophores extending from the dorsal margin of the humeral spot to below the lateral stripe. Habitat data and environmental impacts caused by the construction of reservoirs for hydroelectric projects and other threats in the area are included, as well as a key to all species Hemibrycon present in the Magdalena River Basin. The synonymy of H. pautensis with H. polyodon is discussed and H. pautensis is revalidated. PMID:24027929

Aspects of the reproductive biology of Astyanax janeiroensis in the Ubatiba river in Maricá, RJ, Brazil were evaluated in order to ascertain whether the strategy adopted by the species is causally related to environmental variables. Specimens were collected on a monthly basis from October 1994 to September 1995, through electrofishing. The Sex ratio was not significantly different from the expected frequency of 1:1 (G = 1.29; p > 0.50); nonetheless, considering three standard length classes, significantly larger numbers of females were recorded for the higher SL class (G = 11.07; p < 0.01). Size at first maturation showed no significant differences between sexes. Length-weight ratio analyses showed negative allometry for males and isometry, for females. Length structure was significantly different between sexes, suggesting that females are larger than males (D = 0.027, p < 0.01). Reproductive specimens were recorded during nine months of the annual cycle. Seasonal variations of reproductive specimens belonging to two different standard length classes displayed an asynchronous behavior, with larger specimens having a longer reproductive period and smaller ones reproducing for fewer months during the annual cycle. High values of fecundity (F), varying from 3169 to 18714 oocytes, were recorded for fish of 9.1 and 10.2 cm lengths, respectively. The correlation between weight and number of oocytes/unit of weight was positive, indicating that larger specimens produced more eggs. PMID:16532189

We investigated the effects of acidic pH and acute aluminum (Al) exposure on the metabolic substrates of Astyanax bimaculatus, and on the ability of these animals to recover in clean water. After an acclimation period, sexually mature A. bimaculatus females were sorted into six glass aquaria with three experimental groups: control in neutral pH (7.0), acidic pH (5.5), and Al (0.5 mg·L(-1)) in acidic pH (5.5). After a 96 h treatment, 10 animals from each experimental group were sampled and the rest were returned to clean water in neutral pH without Al for a recovery period of 96 h. The acidic pH, either alone or combined with Al, decreased T4 levels, whereas Al exposure increased T3 levels. Recovery of T3 levels occurred after 96 h. Al exposure decreased ovary and plasma proteins, muscle glycogen contents, and hepatic lipids due to lipoperoxidation. In the recovery phase, lipids decreased in most tissues, probably to re-establish ovary protein and hepatic glycogen. A. bimaculatus prioritized the use of energetic resources during acclimatization to Al instead of prioritizing reproduction, thereby avoiding the ovulation of impaired eggs. PMID:22960447

B chromosomes constitute a heterogeneous mixture of genomic parasites that are sometimes derived intraspecifically from the standard genome of the host species, but result from interspecific hybridization in other cases. The mode of origin determines the DNA content, with the B chromosomes showing high similarity with the A genome in the first case, but presenting higher similarity with a different species in the second. The characid fish Moenkhausia sanctaefilomenae harbours highly invasive B chromosomes, which are present in all populations analyzed to date in the Parana and Tietê rivers. To investigate the origin of these B chromosomes, we analyzed two natural populations: one carrying B chromosomes and the other lacking them, using a combination of molecular cytogenetic techniques, nucleotide sequence analysis and high-throughput sequencing (Illumina HiSeq2000). Our results showed that i) B chromosomes have not yet reached the Paranapanema River basin; ii) B chromosomes are mitotically unstable; iii) there are two types of B chromosomes, the most frequent of which is lightly C-banded (similar to euchromatin in A chromosomes) (B1), while the other is darkly C-banded (heterochromatin-like) (B2); iv) the two B types contain the same tandem repeat DNA sequences (18S ribosomal DNA, H3 histone genes, MS3 and MS7 satellite DNA), with a higher content of 18S rDNA in the heterochromatic variant; v) all of these repetitive DNAs are present together only in the paracentromeric region of autosome pair no. 6, suggesting that the B chromosomes are derived from this A chromosome; vi) the two B chromosome variants show MS3 sequences that are highly divergent from each other and from the 0B genome, although the B2-derived sequences exhibit higher similarity with the 0B genome (this suggests an independent origin of the two B variants, with the less frequent, B2 type presumably being younger); and vii) the dN/dS ratio for the H3.2 histone gene is almost 4-6 times higher for B chromosomes than for A chromosome sequences, suggesting that purifying selection is relaxed for the DNA sequences located on the B chromosomes, presumably because they are mostly inactive. PMID:26934481

Annulotrematoides bryconi sp. n. is described and illustrated from specimens collected from gills of characiform fish, Brycon cephalus (Günther, 1869), in pisciculture ponds from Pirassununga, São Paulo, Brazil. Diagnostic characters of the new species are the tegument of trunk showing annulations, except on the cephalic regiona, and copulatory complex comprising sclerotized male copulatory organ coiled in 1 1/2 rings. This is the first record of monogeneans parasitic on the gills of B. cephalus. PMID:14971596

Cytogenetic data are presented for Astyanax altiparanae populations from three Brazilian hydrographic systems. The chromosomal data obtained in A. altiparanae support the hypothesis of diploid number conservation. However, small differences in the karyotype formula and number of nucleolar organizer regions were observed in these populations. The apparent karyotypical similarity among the studied populations strongly suggests a close relationship among them with some chromosomal divergences due to gene flow restriction. PMID:21637456

This paper presents a survey of the cell groups in the telencephalon of the teleost Astyanax hubbsi, based on series of transverse sections stained with the Nissl-Klüver-Barrera and Bodian procedures. The work was conducted for two reasons. Firstly, it was intended to determine the contribution of the forebrain of blind cave fish to certain forms of behavior. An understanding of the anatomy of the telencephalic organization is essential for such a neuroethological approach. The second purpose was to provide the cytoarchitectural basis for the experimental analysis of the fiber connectivity of the telencephalon of A. hubbsi. Furthermore, information about the forebrain of characids is widely lacking, and this study may thus provide important knowledge about the cellular organization of characid forebrains for comparative anatomists. The brain of A. hubbsi is slender and elongated. Both optic nerves and optic tectum are reduced. Three longitudinal sulci-s. ypsiliformis, s. externus and s. limitans telencephali-can be distinguished in the telencephalon. A fiber lamina reaching from the s. externus to the s. limitans telencephali separates the area dorsalis (D) from the area ventralis telencephali (V). The two hemispheres are connected by fibers decussating in the anterior commissure. Although cross sections revealed no distinct fiber laminae between cytoarchitectonic components, 17 cell masses could be delineated: ten of these belong to D, seven to V. The topological analysis yielded the following results. The dorsal telencephalon D consists of three longitudinal columns, termed pars medialis (Dm), pars dorsalis and centralis (Dd and Dc) considered together, and par lateralis (Dl), which converge into a uniform posterior part (Dp). The columns can be divided into several subregions: Dm1 and Dm2, as well as Dlv and Dld, precommissurally, Dm3 and Dm4 postcommisurally. At polus posterior levels nucleus tenia can be identified. The ventral telencephalon (V) is arranged precommissurally in a periventricular neuronal column consisting of a dorsal (Vd) and ventral (Vv) part. Additionally, a lateral part (VI) is delineated. More caudally, a supracommissural part (Vs), a commissural part (Vc), a posterior part (Vp), and nucleus entopeduncularis are identified. This topological organization reflects many features characteristic for actinopterygian forebrains. PMID:8980850

B chromosomes constitute a heterogeneous mixture of genomic parasites that are sometimes derived intraspecifically from the standard genome of the host species, but result from interspecific hybridization in other cases. The mode of origin determines the DNA content, with the B chromosomes showing high similarity with the A genome in the first case, but presenting higher similarity with a different species in the second. The characid fish Moenkhausia sanctaefilomenae harbours highly invasive B chromosomes, which are present in all populations analyzed to date in the Parana and Tietê rivers. To investigate the origin of these B chromosomes, we analyzed two natural populations: one carrying B chromosomes and the other lacking them, using a combination of molecular cytogenetic techniques, nucleotide sequence analysis and high-throughput sequencing (Illumina HiSeq2000). Our results showed that i) B chromosomes have not yet reached the Paranapanema River basin; ii) B chromosomes are mitotically unstable; iii) there are two types of B chromosomes, the most frequent of which is lightly C-banded (similar to euchromatin in A chromosomes) (B1), while the other is darkly C-banded (heterochromatin-like) (B2); iv) the two B types contain the same tandem repeat DNA sequences (18S ribosomal DNA, H3 histone genes, MS3 and MS7 satellite DNA), with a higher content of 18S rDNA in the heterochromatic variant; v) all of these repetitive DNAs are present together only in the paracentromeric region of autosome pair no. 6, suggesting that the B chromosomes are derived from this A chromosome; vi) the two B chromosome variants show MS3 sequences that are highly divergent from each other and from the 0B genome, although the B2-derived sequences exhibit higher similarity with the 0B genome (this suggests an independent origin of the two B variants, with the less frequent, B2 type presumably being younger); and vii) the dN/dS ratio for the H3.2 histone gene is almost 4–6 times higher for B chromosomes than for A chromosome sequences, suggesting that purifying selection is relaxed for the DNA sequences located on the B chromosomes, presumably because they are mostly inactive. PMID:26934481

Comprising a large number of species, the genus Astyanax has been intensively studied by several approaches to elucidate its evolutionary relationships. Such studies have demonstrated that many nominal species are artificial clusters where distinct taxa are grouped under the same denomination. Astyanax aff. fasciatus stands out due to its high karyotypic diversity, since cytogenetic studies have reported three standard cytotypes (2n = 46, 48, and 50), as well as cases of sympatry between cytotypes, variant cytotypes, and B chromosomes. In this study, we attempted to evaluate the reliability of the chromosomal differences in relation to the analysis of the ATPase6/8 mitochondrial DNA (mtDNA) sequence, thereby providing subsidies to the evolutionary reconstruction of this group. Nine populations from four distinct hydrographic basins along Southeastern Brazil were analyzed. These are the first cytogenetic data collected for four of them. Fluorescent in situ hybridization with 5S rDNA probe evidenced the presence of a standard phenotype for the group and the existence of a new arrangement in the individuals from Ribeira de Iguape River. Besides the karyotypic variation, the genetic distance was low among the studied populations and some aspects of the evolutionary relationships among distinct cytotypes/populations could be ascertained by phylogeographic studies. The incipient molecular structuring of certain cytotypes in different hydrographic basins indicates the role of different evolutionary processes on the diversification of the group. PMID:27148810

Studies of genotoxicity in fish caused by cyanobacterial microcystins can be useful both in determining the sensitivity of native species, as well as comparing exposure routes. The genotoxicity caused by the microcystins LR and LA from a bloom collected in a eutrophic lake, was revealed in the fish Astyanaxbimaculatus, a native species from South America. LC50 (72 h) was determined as 242.81 μg L -1 and LD50 (72 h) as 49.19 μg kg -1 bw. There was a significant increase of DNA damage in peripheral erythrocytes, following intraperitoneal injection (ip) with tested concentrations of 24.58 μg kg -1 bw and 36.88 μg kg -1 bw, as well as through body exposure to a concentration of 103.72 μg L -1 . Micronucleus (MN) induction was observed after ip injections of 24.58 μg kg -1 bw and 36.88 μg kg -1 bw for 72 h, as well as following body exposure for 72 at 103.72 μg L -1 . Thus, both exposure routes resulted in MN induction and DNA damage. Apoptosis-necrosis testing was carried out only by ip injection with concentrations of 24.58 μg kg -1 bw and 36.88 μg kg- 1 bw. Exposure to microcystins at lower concentrations induced more apoptosis than necrosis in peripheral erythrocytes, whereas exposure at higher concentrations gave rise to both conditions. Thus, Astyanax bimaculatus can be considered as a species sensitive to the genotoxic effects caused by microcystins. PMID:21637586

This study described the variations seasonal and ontogenetic of Salminus hilarii diet. Samples were collected in the Sorocaba River, São Paulo, Brazil, one of the few rivers where individuals of the species still occur in a higher frequency. The preys consumed were analyzed by Importance Alimentary Index (AIi). To determine similarities between year seasons, the AIi data were analyzed by the Morisita-Horn index and reduced in cluster analysis, along with a statistical comparison made by one-way ANOSIM test (5%). The feeding activity was analyzed according to the stomach repletion index and compared among the year seasons using non parametric variance analysis Kruskal-Wallis test (5%). Comparison of prey consumed between immature and adult individuals was made by Spearman correlation (5%). A Pearson correlation (5%) was applied between the standard length of the fish and prey consumed, as well as between the mouth and prey heights. The analyzes of stomach contents showed that the diet of this species was exclusively piscivorous, with significant difference of prey consumption during the period, the same happening among adult and immature individuals. It was observed that these fishes use to swallow their prey whole and that significant correlations between size of predator and prey size can be observed. There is also correlation between the mouth height and the maximum prey depth. Salminus hilarii feeds on the available prey, and the species food composition and feeding activity depends on prey`s abundance, their size and morphology, as do the water temperatures. PMID:26421770

Establishing phylogenetic relationships of miniature fishes is challenging in taxa with developmental truncation. Within the Characiformes, developmental truncation appears to be relatively rare, with the Neotropical genus Priocharax being an example. Priocharax includes three miniature species among the smallest of the order and has been hypothesized to belong to the Heterocharacinae. The pronounced reduction in its skeleton, however, prevented a clearer evaluation of its relationships. The present detailed osteological study was designed to address this question and revealed that 21 bones are absent and nine other skeletal structures are simplified in Priocharax when compared to other characids. Comparison of the skeleton of adult Priocharax with early developmental stages of other characids demonstrated that most of the absences and simplifications can be interpreted as developmental truncations. The most striking developmental truncations are in the pectoral girdle, in which the endoskeleton remains entirely cartilaginous. Other interesting truncations are in the ethmoid region of the skull, infraorbital series, and Weberian apparatus, in which the claustrum is absent. Our study also revealed some unusual sexual dimorphisms in the pelvic girdle. Two cladistic analyses were performed to assess the relationships of Priocharax within the Heterocharacinae. The first consisted of a traditional analysis in which all absences and reductions of Priocharax were coded in the same way as in the remaining taxa. This resulted in three equally most parsimonious topologies, all of which have Priocharax as the most basal taxon of the Heterocharacinae. The second analysis incorporated ontogenetic information, and most absences and reductions of Priocharax were reinterpreted as apomorphic conditions and thus, coded differently from similar conditions in outgroups. This resulted in a single phylogenetic hypothesis with Priocharax and Gnathocharax as sister groups based on seven synapomorphies. Our approach demonstrates the importance of developmental studies to better understand morphological evolution of miniaturized, truncated taxa, and to generate hypotheses of their relationships. PMID:26395188

Over the course of one year, undescribed specimens of Gyrodactylus were recovered from banded tetra, Astyanax aeneus collected in the La Antigua and Nautla river basins in central Veracruz, Mexico. Parasites were processed for morphometric and molecular analyses. Morphometrically, Gyrodactylus samples collected in the La Antigua river had slightly smaller haptoral structures than those collected from the Nautla river. During the 12month-collection of samples, however, water temperature varied considerably (ca. 20°C to 30°C), and this abiotic factor is known to affect the size of gyrodactylid attachment structures. Moreover, no clear discrimination was possible between individual parasites collected from the two rivers based on the morphology of the marginal hook, which is recognised as a very informative character to discriminate between species. The morphology of the ventral bar, however, differed between specimens from both rivers: worms from Nautla all had long, rounded processes on the ventral bar, which formed a relatively closed angle with the dorsal edge of the bar proper, while most - but not all - specimens from La Antigua had comparatively slender processes forming a more open angle with respect to the ventral bar. Phylogenetic analyses based on the sequences of the ITS1, 5.8S rRNA gene, and ITS2 of gyrodactylids indicated the existence of two distinct, well-supported lineages whose sequences differ by >4%, one of which was only found in the Nautla basin, while the other was collected in both river systems. A posteriori, principal component analysis (PCA) of the morphometric data of sequenced specimens indicated that features of the dorsal bar, the hamuli and the ventral bar enable discrimination between the two phylogenetic lineages. Based on these independent sources of information (morphometric and molecular data), two new species of Gyrodactylus are described: Gyrodactyluspakan n. sp. and Gyrodactylusteken n. sp. The phylogenetic relationships of both new species to other gyrodactylids infecting characiformes (for which molecular data are available) are presented, which suggests that their closest relative is Gyrodactylus carolinae, a parasite of Characidium lanei in Brazil. PMID:27208885

Astyanax altiparanae fish species is considered very generalist and opportunist, occupying different types and sizes of environments. This characteristic turns it very appropriate as bioindicator or biomarked. Therefore, in this work, A. altiparanae fish species was used to identify populations by using the Fourier transform infrared spectroscopy directly in its scales. The discriminant analysis applied in the infrared spectra demonstrated a significant differentiation among the analyzed populations, with the first and second canonical roots explain together 100% of the data variation. The obtained results were correlated with environmental descriptors and diet of fishes, and a better agreement was obtained when spectroscopic data were compared with the composition of food present in the fish stomachs. However, this study indicates that the combination of infrared absorption spectroscopy with discriminant analysis is a very appropriate methodology to be used in fish scales as bioindicator for intraspecific study.

The genus Astyanax is relatively common and encompasses various similar taxa forming a highly complex group that is difficult to precisely delimit. The present study aims to analyze cytogenetically and morphologically specimens of A. altiparanae belonging to distinct populations of the Iguatemi River Basin, Mato Grosso do Sul State, Brazil, for a better understanding of the evolutionary processes in this fish group. This study analysed 32 specimens of Astyanax altiparanae from Iguatemi River basin, MS, Brazil: 24 from the Agua Boa stream and 8 from the Santa Maria stream. All specimens showed a diploid number equal to 50 chromosomes with differences in the karyotypic formula and types of chromosomes bearing the NOR between the two localities. The constitutive heterochromatin showed interstitial markings evident in the region of some chromosomes in both populations. In the morphometric analysis, the first three axes were retained for interpretation which together explained 81% of variance, showing morphometric distinction between populations. Chromosomal and morphometric data obtained may be useful for taxonomic and phylogenetic studies in this group of fish. PMID:25403073

From the examination of extensive comparative material currently identified as M. jamesi we verified that there are, at least, three new species under this name. These, along with M. jamesi and M. justae, form what we herein called the M. jamesi species complex, by sharing the following group of characters: a short maxilla, with its distal margin not exceeding anterior third of the second infraorbital; first through third teeth of the inner row of premaxilla and first and second dentary teeth with cusps arranged in a pronounced arch, humeral spot positioned between the fourth and seventh scales of the lateral line and extending up to four scale rows above the lateral line and one scale row below the lateral line, and a vertically oval to round spot at the base of the caudal fin rays. Moenkhausia ischyognatha sp. n., from Rio Xingu basin, differs from the other species of the complex by its lower head depth. Moenkhausia alesis sp. n., from the river system Tocantins-Araguaia, differs from M. jamesi, M. ischyognatha, and M. sthenosthoma by the number of scale rows above the lateral line. Moenkhausia sthenosthoma sp. n., from the Rio Madeira basin, differs from M. jamesi by the number of scale rows between the lateral line and the midventral scale series. Moenkhausia justae can be diagnosed from the other species of the complex by having a tri to pentacuspidate tooth on the maxilla. PMID:26250196

Abstract Hemibrycon sanjuanensis, new species, is described from the upper San Juan River drainage, Pacific versant, Colombia. It is distinguished from Hemibrycon boquiae, Hemibrycon brevispini, Hemibrycon cairoense, Hemibrycon colombianus, Hemibrycon mikrostiktos, Hemibrycon metae, Hemibrycon palomae, Hemibrycon rafaelense and Hemibrycon tridens by the presence of a circular or oblong humeral spot that is located two scales posterior to the opercle (vs. 3–4 scales in Hemibrycon palomae, Hemibrycon rafaelense, Hemibrycon brevispini and Hemibrycon cairoense, and 0–1 scales, in Hemibrycon metae and Hemibrycon boquiae). It further differs from Hemibrycon colombianus in having a round or oblong humeral spot (vs. rectangular). It differs from Hemibrycon beni, Hemibrycon dariensis, Hemibrycon divisorensis, Hemibrycon helleri, Hemibrycon huambonicus, Hemibrycon inambari, Hemibrycon jabonero, Hemibrycon jelskii, Hemibrycon mikrostiktos, Hemibrycon polyodon, Hemibrycon quindos, Hemibrycon raqueliae, Hemibrycon santamartae, Hemibrycon surinamensis, Hemibrycon taeniurus, Hemibrycon tridens, and Hemibrycon yacopiae in having melanophores on the posterior margins of the scales along the sides of body (vs. lacking melanophores on margins of scales along entire length of the sides of body). The new species differs from all congeners mentioned above in having, among other features, six teeth in the outer premaxillary row arranged in a straight line (vs. five or fewer teeth not arranged in straight line except Hemibrycon cairoense with two to six teeth in the outer premaxillary row). PMID:25493068

The synthetic hormone, 17-α-methyltestosterone (MT), is used in fish hatcheries to induce male monosex. Androgenic effects on various fish species have been reported; however, few studies have assessed possible genotoxic effects, although there are concerns about such effects in target and non-target species. We evaluated genotoxic and gonadal effects of MT in adult tilapia (Oreochromis niloticus) and Astyanax bimaculatus (a common native non-target fish in Brazil). Fish were fed for 28 days with ration containing MT (60 mg/L), a normal dose used in fish farming. Evaluation of MT genotoxicity was carried out through micronucleus test, nuclear abnormality, and comet assay analyses on peripheral erythrocyte cells collected by cardiac puncture. There were no significant differences in micronucleus frequencies and DNA damage in both species; however, MT caused cytogenetic toxicity in the non-target species, A. bimaculatus, with significantly increased erythrocyte nuclear abnormalities. Histopathological analyses of the female gonads of O. niloticus revealed that MT significantly inhibited the development of mature oocytes, while in A. bimaculatus it provoked significant inhibition of spermatozoa production. We concluded that discharge of fish-hatcheries water onto the surface of aquatic ecosystems should be avoided due to risks to reproduction of native species. PMID:24085447

The sublethal effects of water-soluble fraction of gasoline (WSFG, 1.5 % v/v) were evaluated in the freshwater fish, Astynax altiparanae, after acute exposure (96 h) under a semi-static system. In addition, the recovery process was assessed in the fish following contaminant depuration. Recovery treatments were carried out with gradual depuration (GD), consisting of 7 days in the WSFG, followed by 8 days in clean water; and treatments with total depuration in clean water for 15 (DEP 15) and 30 days (DEP 30). The effects were evaluated through the piscine micronucleus test and by differential counting of organic defense cells. Acute exposure increased the frequency of neutrophils. In the GD treatment, the thrombocyte count and erythrocytic nuclear abnormalities (ENA) increased. In the DEP 15 treatment, there was a reduction of ENA; and following 30 days of depuration (i.e., DEP 30), the number of lymphocytes increased and the thrombocyte count remained high. These results indicate a long-term response to a condition of stress from WSFG. PMID:27189358

Hemibryconsanjuanensis, new species, is described from the upper San Juan River drainage, Pacific versant, Colombia. It is distinguished from Hemibryconboquiae, Hemibryconbrevispini, Hemibryconcairoense, Hemibryconcolombianus, Hemibryconmikrostiktos, Hemibryconmetae, Hemibryconpalomae, Hemibryconrafaelense and Hemibrycontridens by the presence of a circular or oblong humeral spot that is located two scales posterior to the opercle (vs. 3-4 scales in Hemibryconpalomae, Hemibryconrafaelense, Hemibryconbrevispini and Hemibryconcairoense, and 0-1 scales, in Hemibryconmetae and Hemibryconboquiae). It further differs from Hemibryconcolombianus in having a round or oblong humeral spot (vs. rectangular). It differs from Hemibryconbeni, Hemibrycondariensis, Hemibrycondivisorensis, Hemibryconhelleri, Hemibryconhuambonicus, Hemibryconinambari, Hemibryconjabonero, Hemibryconjelskii, Hemibryconmikrostiktos, Hemibryconpolyodon, Hemibryconquindos, Hemibryconraqueliae, Hemibryconsantamartae, Hemibryconsurinamensis, Hemibrycontaeniurus, Hemibrycontridens, and Hemibryconyacopiae in having melanophores on the posterior margins of the scales along the sides of body (vs. lacking melanophores on margins of scales along entire length of the sides of body). The new species differs from all congeners mentioned above in having, among other features, six teeth in the outer premaxillary row arranged in a straight line (vs. five or fewer teeth not arranged in straight line except Hemibryconcairoense with two to six teeth in the outer premaxillary row). PMID:25493068

The genus Hyphessobrycon is included within the subfamily Tetragonopterinae. The species are generally small, do not exceed 70mm of standard length, are economically important as ornamental fish, with 128 valid species distributed from Southern Mexico to Rio La Plata in Argentina. The collections of fish were made with seines, in a single biotope, along shore in backwaters and working downstream. Measurements of the specimens were taken point to point with digital calipers. Observations of bone and cartilage structures were made on cleared and stained (C&S) specimens. The morphometric relationships between species were explored using a principal component analysis (PCA)using 21 variables. We described a new species, Hyphessobrycon chocoensis, from the Telembi River drainage of the Pacific versant of Colombia. The new species, Hyphessobrycon chocoensis, is distinguished from congeners not of the "flammeus" species group by: having a diffuse humeral spot, in lacking a dark spot on the dorsal fin and caudal peduncle. It is distinguished from members its species group by the number of rays in the dorsal fin (ii, 8, i), by the number of branched anal-fin rays (25-26) and by having a diffuse humeral spot. It differs from H. tortuguerae in the number of teeth on the maxilla (1-2), by the number of predorsal scales and the high number of scales between the lateral line and the anal fin (6-7). Hyphessobrycon chocoensis can be distinguished from the other known species of Hyphessobrycon from the Pacific Coast of Colombia in having: a high number of pored lateral-line scales, by the snout to dorsal-fin length, by caudal-peduncle depth and by eye diameter. In addition, it differs from H. columbianus by the distance from the dorsal fin to the anal fin, by the length of the upper jaw, and by snout length. It differs from H. condotensis in having a high number of scales between the lateral line and the dorsal fin, and by the number of simple rays in the anal fin. H. chocoensis is distinguished from H. sebastiani by the number of transverse scales and the number of scales between the lateral line and the dorsal fin. A taxonomic key is provided to aid with the identification of the species of Hyphessobrycon from the Pacific Coast of Colombia. PMID:23894972

Background Mesoamerica is one of the world's most complex biogeographical regions, mostly due to its complex geological history. This complexity has led to interesting biogeographical processes that have resulted in the current diversity and distribution of fauna in the region. The fish genus Astyanax represents a useful model to assess biogeographical hypotheses due to it being one of the most diverse and widely distributed freshwater fish species in the New World. We used mitochondrial and nuclear DNA to evaluate phylogenetic relationships within the genus in Mesoamerica, and to develop historical biogeographical hypotheses to explain its current distribution. Results Analysis of the entire mitochondrial cytochrome b (Cytb) gene in 208 individuals from 147 localities and of a subset of individuals for three mitochondrial genes (Cytb, 16 S, and COI) and a single nuclear gene (RAG1) yielded similar topologies, recovering six major groups with significant phylogeographic structure. Populations from North America and Upper Central America formed a monophyletic group, while Middle Central America showed evidence of rapid radiation with incompletely resolved relationships. Lower Central America lineages showed a fragmented structure, with geographically restricted taxa showing high levels of molecular divergence. All Bramocharax samples grouped with their sympatric Astyanax lineages (in some cases even with allopatric Astyanax populations), with less than 1% divergence between them. These results suggest a homoplasic nature to the trophic specializations associated with Bramocharax ecomorphs, which seem to have arisen independently in different Astyanax lineages. We observed higher taxonomic diversity compared to previous phylogenetic studies of the Astyanax genus. Colonization of Mesoamerica by Astyanax before the final closure of the Isthmus of Panama (3.3 Mya) explains the deep level of divergence detected in Lower Central America. The colonization of Upper Mesoamerica apparently occurred by two independent routes, with lineage turnover over a large part of the region. Conclusion Our results support multiple, independent origins of morphological traits in Astyanax, whereby the morphotype associated with Bramocharax represents a recurrent trophic adaptation. Molecular clock estimates indicate that Astyanax was present in Mesoamerica during the Miocene (~8 Mya), which implies the existence of an incipient land-bridge connecting South America and Central America before the final closure of the Isthmus of Panama (~3.3 Mya). PMID:19102731

The location of 18S and 5S rDNA sites was determined in eight species and populations of the fish genus Triportheus by using fluorescent in situ hybridization (FISH). The males and females of all species had 2n = 52 chromosomes and a ZZ/ZW sex chromosome system. A single 18S rDNA site that was roughly equivalent to an Ag-NOR was detected on the short arms of a submetacentric pair in nearly all species, and up to two additional sites were also observed in some species. In addition, another 18S rDNA cluster was identified in a distal region on the long arms of the W chromosome; this finding corroborated previous evidence that this cluster would be a shared feature amongst Triportheus species. In T. angulatus, a heterozygotic paracentric inversion involving the short arms of one homolog of a metacentric pair was associated with NORs. The 5S rDNA sites were located on the short arms of a single submetacentric chromosomal pair, close to the centromeres, except in T. auritus, which had up to ten 5S rDNA sites. The 18S and 5S rDNA sites were co-localized and adjacent on the short arms of a chromosomal pair in two populations of T. nematurus. Although all Triportheus species have a similar karyotypic macrostructure, the results of this work show that in some species ribosomal genes may serve as species-specific markers when used in conjunction with other putatively synapomorphic features. PMID:21637644

The fish genus Astyanax is widespread throughout the Neotropical region and is one of the most species-rich genera of the Characiformes. Cytogenetic studies of Astyanax have revealed marked intra- and interspecific diversity, with the identification of various species complexes. In this report, we describe the karyotypic structure of two sympatric species of Astyanax (Astyanax sp. and Astyanax aff. fasciatus) from the Middle Contas River basin in the northeastern Brazilian state of Bahia. Both species had 2n = 48 but differed in their karyotypic formulae. Small heterochromatic blocks and multiple nucleolar organizer regions (NORs) were identified in both species. Terminal CMA(3) (+)/DAPI(-) signals were observed in Astyanax sp. and A. aff. fasciatus, mostly coincident with NORs. These results show that chromosomal markers can be used to identify species in this fish complex. These markers can provide useful information for evolutionary studies and investigations on the mechanisms of chromosomal diversity in Astyanax. PMID:23271941

Oligosarcus amome is described from tributaries of the arroyo Yabotí-Guazú, río Uruguay basin, Misiones Province, Argentina. This new species can be distinguished from all its congeners by the following combination of characters: presence of two conspicuous series of teeth on premaxilla bearing pentacuspidate teeth in the outer series. Oligosarcus amome is the sister taxon of all remaining analyzed species of the genus excepting O. itau. PMID:25662145

The fish genus Astyanax is widespread throughout the Neotropical region and is one of the most species-rich genera of the Characiformes. Cytogenetic studies of Astyanax have revealed marked intra- and interspecific diversity, with the identification of various species complexes. In this report, we describe the karyotypic structure of two sympatric species of Astyanax (Astyanax sp. and Astyanax aff. fasciatus) from the Middle Contas River basin in the northeastern Brazilian state of Bahia. Both species had 2n = 48 but differed in their karyotypic formulae. Small heterochromatic blocks and multiple nucleolar organizer regions (NORs) were identified in both species. Terminal CMA3+/DAPI− signals were observed in Astyanax sp. and A. aff. fasciatus, mostly coincident with NORs. These results show that chromosomal markers can be used to identify species in this fish complex. These markers can provide useful information for evolutionary studies and investigations on the mechanisms of chromosomal diversity in Astyanax. PMID:23271941

Brycon pesu is a small-sized fish distributed throughout the Amazon and Orinoco Basins and other coastal basins of northeastern South America. Brycon cf. pesu specimens from the Araguaia-Tocantins Basin are currently separated into two morphotypes, Brycon sp1 and Brycon sp2, owing to different coloration of their anal fin. Brycon sp2 has a reddish margin stripe on the anal fin which morphologically distinguishes it from Brycon sp1. In the present research, nuclear and mitochondrial markers were used to test the hypothesis that the Brycon sp1 and Brycon sp2 morphotypes are distinct species. Specimens from the two morphotypes were collected from the Lajeado Hydroelectric Plant and the Palmas River in the Araguaia-Tocantins Basin. Thirty-five loci obtained by the amplification of five inter-simple sequence repeat primers were analyzed but no species-specific bands were detected. Electrophoretic profiles obtained from 5S rDNA non-transcribed spacer amplification failed to show any differentiation in morphotypes. These results were corroborated by nucleotide sequence analysis of the mtDNA control region, in which 24 polymorphic nucleotide sites, representing a polymorphism rate of only 5%, were detected. The low rates of polymorphism detected by inter-simple sequence repeat, non-transcribed spacer and mtDNA D-loop markers strongly reject the hypothesis that the two morphotypes Brycon sp1 and Brycon sp2 represent distinct species within Brycon cf. pesu. Further studies are needed to obtain conclusive data on the notion that the coloration of the anal fin is an intraspecific polymorphism, possibly related to environmental factors. PMID:18273825

Astyanax has been the subject of extensive cytogenetic studies due to its wide karyotypic diversity. This genus comprises species complexes, namely groups of fish of difficult morphological differentiation, such as the bimaculatus complex, which includes the characids with a rounded humeral spot. Thence, the present study proposed to accomplish a cytogenetic characterization of two species of this complex: A. asuncionensis and A. altiparanae, aiming to find chromosomal markers that differentiate these species, as well as achieve a better understanding of the karyotype evolution in the genus. For this we used different techniques of chromosome banding as C-banding, impregnation by silver nitrate, fluorochrome staining and FISH with 18S rDNA probe. This is the first cytogenetic study in A. asuncionensis, from Miranda river, which presented 2n = 50 and 18 m + 22sm + 6st + 4a (FN = 96) and single NORs. The populations of A. altiparanae also presented 2n = 50, but with different karyotypic formulae: the population of the Quexada river presented 16 m + 24sm + 4st + 6a (FN = 94) and the Esperança stream and Jacutinga river showed 16 m + 20sm + 4st + 10a (FN = 90). All analyzed populations showed an interindividual variation in the number and location of the nucleolar organizer regions (NORs). Single and multiple NORs were detected either by impregnation with silver nitrate or by FISH with 18S rDNA probe. After C-banding, the two species differed in relation to the composition and heterochromatin distribution. The meiotic cells of A. altiparanae male individuals were also analyzed, showing that, despite the high karyotype variability, chromosome pairing occurs normally. The data show that A. altiparanae and A. asuncionensis share some characteristics with other species of the bimaculatus complex, suggesting a close phylogenetic relationship among those species. However, some features can be used as differentiation chromosomal markers in altiparanae/asuncionensis morphotypes, which could result from a natural speciation process. PMID:27456346

This study characterizes by transmission electron microscopy (TEM) and morphometric features the myxozoan Myxobolus cuneus (Myxosporea) in Piaractus mesopotamicus and reports the skeletal muscle and kidney as site of infection. The register was based in 21 young fish from intensive fish farming in Southeast Brazil and the spores were analyzed in fresh-mounted slides of the infected organs stained with Toluidine blue and processed as usual for TEM. It differs from Myxobolus cunhai from the fish host and different polar capsule size, and from Myxobolus serrasalmi on the pyriform spore shape and an oval macrospore, differently to that reported in this study. Morphometric characteristics and TEM study confirmed the present material as M. cuneus. PMID:27021179

Phenotypic variation is important for evolutionary processes because it can allow local adaptation, promote genetic segregation, and ultimately give rise to speciation. Lacustrine systems provide a unique opportunity to study the mechanisms by which sister species can co-occur by means of ecological segregation. The fish genus Astyanax is characterized by high levels of phenotypic variability, providing an excellent model for the study of local specialization. Here, we analyze the morphological specializations through geometric morphometrics of two sympatric species described as different genera: Bramocharax caballeroi endemic to Lake Catemaco, and the widely distributed Astyanax aeneus. Additionally, we assess the correlation between phenotypic and genetic structure, and the phylogenetic signal of morphological variation. We examined body size and shape variation in 196 individuals and analyzed mitochondrial cytochrome b sequences in 298 individuals. Our results confirm the striking morphological divergence among the sympatric characids. Differences between them were mainly found in the body depth and profile and orientation of the head, where B. caballeroi in contrast with the A. aeneus, presented a fusiform body and an upward mouth. Moreover, different growth trajectories were observed among morphotypes, suggesting that a heterochronic process could be involved in the diversification of our study system. Morphological differences did not correspond with the molecular differentiation, suggesting high levels of homoplasy among the lineages of B. caballeroi morphs. PMID:24470053

A new species of Bryconops is described from a right tributary of the lower Tapajós River, State of Pará, Brazil. Bryconops munduruku, sp. nov., differs from its congeners, except B. inpai and B. piracolina, by having a black adipose fin (vs. adipose fin hyaline in alcohol) and, except B. inpai, by possessing two humeral blotches (vs. lack of humeral blotch or only one humeral blotch). Bryconops munduruku differs from B. inpai by having a uniform color pattern on the posterior portion of the side of the body (vs. a dark stripe extending posteriorly from the half of the anal-fin base onto the base of the middle caudal-fin rays). It differs further from B. inpai and B. piracolina by the presence of a black adipose fin that is hyaline along its base (vs. entirely black adipose fin in B. inpai and B. piracolina). The new species is allocated in the subgenus Creatochanes by having a maxillary bone with one to three teeth on both sides, and its posterior extension reaching the junction of second and third infraorbital bones. PMID:26250264

The gametogenesis and reproduction of the matrinxã, Brycon orthotaenia in the São Francisco river, Pirapora Region, Minas Gerais, were studied from December, 1998 to November, 1999. The matrinxã B. orthotaenia is an endemic species in the São Francisco river basin in Brazil and important for commercial fishing. The size of the 1st gonadal maturation, indicated by the total length of the smallest spent males and spawned female, was 32.0 and 40.5 cm respectively. Reproduction occurred from October to January, when high frequencies of females and males at an advanced ripening/mature stage and spawned females were found. The short spawning period and histological characteristics of spawned ovaries containing only oocytes in stages of initial development, along with post-ovulatory and atresic follicles, indicated that Brycon orthotaenia presents total spawning. PMID:16862307

Diaphorocleidus orthodusus n. sp. and Diaphorocleidus kabatai (Molnar, Hanek and Fernando, 1974) Jogunoori, Kritsky, and Venkatanarasaiah, 2004 are detailed from Astyanax orthodus and Astyanax aeneus, respectively. Palombitrema heteroancistrium (Price and Bussing, 1968) is described from specimens collected from A. aeneus, and Urocleidoides strombicirrus (Price and Bussing, 1967) is reported for the first time from A. aeneus and Astyanax fasciatus in Panama. Characithecium costaricensis (Price and Bussing, 1967) n. comb. is detailed based on specimens from A. aeneus. Characithecium costaricensis is characterized by having overlapping gonads, a medioventral vaginal aperture, a copulatory complex consisting of single counterclockwise coil of the copulatory organ that is articulated to the accessory piece, and a haptor having 2 pairs of anchors, dorsal and ventral bars, and 14 hooks. Measurements of body size varied substantially among individual worms, both within and across different host species and locations. However, the morphological differences were insufficient to separate species of Characithecium. This result suggests limited parasite speciation across sympatric species of Astyanax in Mexico and Panama. PMID:19245277

The matrinchã Brycon amazonicus, a commercially important freshwater fish resource, has no heteromorphic sex chromosomes so far described. In the present study, we performed a screening of sex-associated DNA markers in this species, through the use of a random amplified polymorphic DNA (RAPD) assay and a genomic DNA restriction digestion analysis. DNA digestions evidenced no differences between sexes. Sixty-six random primers were used in pooled and individual DNA samples of males and females, and the analysis of the RAPD fingerprints revealed one female sex-associated band. Cloning and sequencing of this band led to the identification of two distinct DNA segments. While one of the isolated fragments showed a significant identity with a described protein gene (phosphatidylinositol glycan anchor biosynthesis, class W), the other fragment, composed of 535 bp, corresponds to a novel DNA marker. Further experiments were performed with this second DNA fragment in order to verify its sex-specificity. Data on dot blot hybridization, using total DNA of both sexes, confirmed its female-specificity in B. amazonicus. A primer set was designed based on its sequence data and used in PCR with DNA samples of this species, leading to diagnose the animals' sexes with a 100 % overall accuracy through a sequence characterized amplified region approach. No amplification results were found for two other species of the genus--B. orbignyanus and B. lundii. The obtained data can lead to the hypothesis that B. amazonicus may present heteromorphic sex chromosomes that should be in an early phase of differentiation. PMID:22527611

Brycon henni is a native species in Magdalena's River basin, and because of its cultural and economic importance, is strongly overexploited. This study aimed to describe the genetic variability and population structure of this species from Nare and Guatapé rivers basins. A total of 195 individuals were collected and DNA extractions were obtained from muscle and blood tissue. Fourteen primers were evaluated with the RAPD technique, being four of them polymorphic, and produced 66 different fragments (63% polymorphism). Besides, using the molecular variance (AMOVA) analysis, the population structure was described for all sites (phi(ST) = 0.297, phi(ST) = 0.163; Nare and Guatapé river basins, respectively), and suggested the importance of the migratory behaviour of the species in the genetic differentiation. Genetic distances among sampled sites showed that most of the genetic differentiation occurred between sites Guatapé and El Cardal with respect to the others. A Mantel Test demonstrated a correlation between genetic and geographic distances (r = 0.431 both of the basins evaluated; r = 0.377, Nare river middle basin), and suggested isolation by distance. The outcomes obtained in this study have valuable implications in species conservation and the genetic variability of natural populations of B. henni, and should be complemented with morphological analyses. PMID:21516650

Two new species of Hyphessobrycon are described from the headwaters of the Tapajós and Xingu River basins, Pará, Brazil. Both new species can be distinguished from congeners by the presence of a vertically elongate humeral blotch, a conspicuous round to vertically oblong caudal-peduncle blotch not extending onto the distal portions of the middle caudal-fin rays, a conspicuous blotch on the central portion of the third infraorbital immediately ventral to the eye, the lack of a conspicuous longitudinal stripe and the lack of sexual dimorphism in the extension of the caudal-peduncle blotch. Hyphessobrycon delimai n. sp. can be distinguished from Hyphessobrycon krenakore n. sp. by the extent of the caudal-peduncle blotch which extends across most of the caudal-peduncle depth (v. restricted to the middle portion of the caudal peduncle), the presence of dark chromatophores uniformly scattered along the length of the interradial membranes of the dorsal, anal and caudal fins (v. concentrated on the distal one-half or one-fourth of the interradial membranes) and the absence of small bony processes on the pelvic and anal fins of mature males (v. small bony processes present). PMID:26660534

A new copepod species, Ergasilus curticrus n. sp. is described based on 14 female specimens collected from the gills of the characid teleost Bryconops giacopinii Fernández-Yépez, captured in the Vichada River Basin in Colombia. The new species has a unique combination of characters including: (i) 2-segmented endopods in legs 1 and 4; (ii) a semi-pinnate, falciform seta on the terminal segment of the first leg exopod; (iii) a 1-segmented fourth leg exopod; (iv) a reduced fifth leg with a single seta; and (v) a circular structure fused to a groove near the lateral margins of the second pedigerous tergite. Only two other known congeners have a 1-segmented leg 4 exopod, E. coatiarus Araujo & Varella, 1998 and E. iheringi Tidd, 1942. Among other characters, they differ from the new species by the lack of a semi-pinnate, falciform seta on the terminal exopodal segment of leg 1 and in the structure and armature of the fifth leg. The prevalence of E. curticrus n. sp. was 13.6% and its mean abundance was 0.4 specimens per host. This is the first new species of Ergasilus Nordmann, 1832 described from the Orinoco River Basin. PMID:26446546

Hyphessobrycon with 129 valid species, is a genus of fish that has a great diversity of species in the Neotropical ichthyofauna, reaches its greatest diversity in the Amazon basin with about 70% of these species, is highly desired by hobbyists because of their beauty and color, and are still meeting new species. We analyzed specimens from the Departamento de Ictiología, Museo de Historia Natural de la Universidad Mayor de San Marcos, Lima, Perú (MUSM); and measurements of the specimens were taken point to point with digital calipers. Observations of bone and cartilage structures were made on cleared and stained (C&S) samples. The morphometric relationships between species using 21 variables were explored using a principal component analysis (PCA). Here we describe two new species, Hyphessobrycon taphorni and H. eschwartzae from the Madre de Dios River drainage, Peru. Hyphessobrycon taphorni sp. n. can be distinguished by the number of dorsal-fin rays (iii, 8), by the number of: pored lateral-line scales (4-5), teeth in the outer premaxillary row (1-2), teeth in the inner premaxillary row (7-8), by: the caudal-peduncle length (11.4-16.4% SL), number of lateral scales (28-29, except from H. loretoensis which has 29-30) and absence of a humeral spot (vs. present), it differs from H. loretoensis by the number of: scales between the lateral line and the anal fin origin (4 vs. 3) and maxillary teeth (2 vs. 3-4), and it differs from H. agulha by the number of branched pectoral-fin rays (11-12 vs. 9-10). Hyphessobrycon eschwartzae sp. n. is distinguished by the number of: simple anal-fin rays (iv), teeth on the dentary (13-15), teeth in the inner premaxillary row (6), teeth in the outer premaxillary row (3, except from H. heterorhabdus and H. loretoensis which have 3-4); it differs from H. loretoensis by the number of: pored lateral-line scales (7 vs. 9-10), scales between the lateral line and the dorsal-fin origin (5 vs. 3-4); it differs from H. agulha in the number of lateral scales (30-31 vs. 33-34), by the number of: predorsal scales (9 vs. 10), maxillary teeth (4 vs. 0-1); in having in life a red lateral stripe above the dark lateral stripe that extends from the posterior part of the opercle to the caudal peduncle (vs. absent) and by the presence of bony hooks in mature males only on the anal fin (vs. hooks on all fins, including the caudal). PMID:23885596

A new species of Hyphessobrycon is described from a tributary of the upper Rio Tapajós, Amazon basin, Mato Grosso, Brazil. Its exuberant colour in life, with blue to purple body and red fins, is appreciated in the aquarium trade. Characters to diagnose the new species from all congeners are the presence of a single humeral blotch, absence of a distinct caudal-peduncle blotch, absence of a well-defined dark mid-lateral stripe on body, the presence of 16-18 branched anal-fin rays, nine branched dorsal-fin rays and six branched pelvic-fin rays. A brief comment on fish species descriptions solely based on aquarium material and its consequence for conservation policies is provided. PMID:27245763

Molecular genetic assessments that consider ecological information, in addition to endogamy levels, genetic diversity, and the genetic differentiation among species and populations, are particularly important for the conservation of biological diversity. Prime candidates for conservation genetic review are those subject to human use, including harvests for the ornamental fish trade. Colorful South American tetra, such as Moenkhausia oligolepis and M. forestii, are good examples of fish species that are widely collected and exported worldwide. This study aimed to evaluate the population-specific characteristics of M. oligolepis and M. forestii by comparing morphometric and molecular analyses based on ISSR markers, to provide information that would facilitate the sustainable management of these 2 species. Seventy-two specimens were collected from the Araguaia-Tocantins and Paraguay River Basins in Brazil. All specimens were measured and analyzed using ISSR markers. Population-exclusive bands were found among the 86 detected bands, while morphometric clusters reflected the geographical distribution of individuals. Correlated genetic and morphological variation supported the presence of 3 distinct groups from tributaries of the Araguaia and Mortes Rivers. Using the same techniques, all M. oligolepis populations were isolated from M. forestii. This study on Moenkhausia presents an interesting example that could be used to construct a framework of South American ichthyodiversity, and reinforces the necessity of habitat conservation to prevent the loss of biological diversity. PMID:25299113

In this study, nitrogen stable isotope (δ(15) N) and total mercury (THg) analyses were conducted on algae, submersed and emergent macrophytes, shrubs and trees, Macrobrachium sp. and Paracheirodon axelrodi collected in three streams that drain a large interfluvial region in the middle Rio Negro, Amazonas State, Brazil. Samples were collected during different hydrological periods over 12 months in lower stream reaches and their headwaters; the latter being characterized by shallow, open-canopy swamps. Additionally, δ(15) N values and mercury concentrations of Paracheirodon simulans and Cichla spp. from the middle Rio Negro were analysed to demonstrate THg biomagnification in the food web. The highest mercury levels of P. axelrodi were found in small individuals, which were collected principally in the low water period. The log10 THg-δ(15) N relationship of vascular plants and algae, Macrobrachium sp., Paracheirodon spp. and Cichla spp. showed significant mercury biomagnification among trophic levels, with regression slopes of 0·15 and 0·25 for the entire food web and heterotrophs-only food web, respectively. The mean ± s.d. THg concentrations for Macrobrachium sp., P. axelrodi, P. simulans and Cichla spp. were 63·6 ± 23·7, 104·5 ± 40·0, 112·3 ± 31·4 and 418·5 ± 188·1 ng g(-1) wet mass, respectively. Elevated levels of mercury found in Paracheirodon spp. and top predators such as Cichla spp. in a remote area far from anthropogenic inputs provide evidence that high mercury concentrations occur naturally in Rio Negro aquatic food webs. PMID:27028984

This study reports for the first time infection with Hysterothylacium sp. larvae in the ornamental fish Hyphessobrycon eques from the Paranapanema River, Jurumirim Reservoir, São Paulo State, Brazil. A sample of 33 specimens of H. eques was collected in October, 2011. Four specimens of H. eques were parasitized by Hysterothylacium sp. larvae in the intestine and coelomic cavity, with prevalence of 12.1%, mean intensity of infection of 1, and mean abundance of 0.121 ± 0.05. A total of 40 unidentified free-living nematodes were found in the stomach content of 17 fish. This fish species is introduced in the Paranapanema River. Invasive species may affect the native fauna given the introduction of pathogens and parasites. This study also complements data on the diet of H. eques due to the records of free-living nematode as part of the stomach content. Infections with Hysterothylacium sp. larvae may affect the biology of this fish and bring about profit losses to aquarists. PMID:26421773

Female individuals of Hyphessobrycon eques were exposed to Diflubenzuron (Dimilin(®)) in order to determine whether exposure to sublethal levels of this insecticide causes changes in gill morphology. Fish were exposed to 0.01, 0.1 and 1.0mgL(-1) for 96h and 17 days and then submitted to pathological and histometric evaluation. Pathological lesions, such as hyperplasia, lamellar fusion, vascular congestion, secondary lamellar disarray, vasodilatation, hemorrhage and increased lamellar epithelium, were significantly more common in the gills of fish exposed to Dimilin(®) than the control. Histometric analysis documented significant changes in blood vessel diameter, primary lamellae width and secondary lamellae length, and the appearance of hemorrhage foci in all concentrations tested. Even at low Dimilin(®) concentrations, the histopathological alteration index was mild to moderate, thereby indicating that the function of this tissue was compromised. These findings indicate that indiscriminate use of Dimilin(®) can adversely affect the structural integrity of the gills of H. eques, which can cause numerous problems for fish farming systems. PMID:27232206

Abstract Two populations of Astyanax altiparanae (Garutti & Britski, 2000) of the Água dos Patos stream/SP and lake Igapó/PR were analyzed. All individuals showed 2n = 50, however, different karyotypic formulae were observed. The population of the Água dos Patos stream showed 8m +24sm+6st+12a (NF=88) and the population of lake Igapó, 8m+28sm+4st+10a (NF=90). Nucleolus organizing regions (AgNORs) were observed in the terminal position on the short and long arm of different chromosomes of both populations, showing a variation from 3 to 4 chromosomes. Fluorescent in situ hybridization (FISH) using 18S rDNA probes revealed only one pair of chromosomes with fluorescent signals in the terminal site on the short arm in the Igapó lake population, while the population of Água dos Patos stream showed 4 fluorescence terminal signals, characterizing a system of simple and multiple NORs, respectively. 5S rDNA fluorescent signals were detected in the interstitial position of a pair of chromosomes in the two studied populations. Some AgNOR sites revealed to be GC-rich when stained with Chromomycin A3 (CMA3), however, AT positive regions were not observed. The data obtained show that, despite the conservation of the diploid number and location of 5S DNAr, differences in both the distribution of 18S rDNA and karyotypic formula among the populations were found, thus corroborating the existing data on chromosome variability in Astyanax altiparanae that can be significant for cytotaxonomy in this group. PMID:24260632

Three species of Ergasilus Nordmann, 1832 are reported from the gills of Salminus spp. in Brazil. Ergasilus salmini Thatcher & Brazil-Sato, 2008 from Salminus brasiliensis Cuvier is redescribed, based on examination of paratypes. The study revealed morphological differences from the original description, especially in the morphology of the cephalothorax and the ornamentation of antenna, antennule and legs. Ergasilus lacusauratus n. sp. described from S. brasiliensis in lake Lagoa Dourada (Paraná) differs from the only known species from this host group, E. salmini, in the shape and size of the cephalothorax and the general morphology of the egg-sacs. Ergasilus sinefalcatus n. sp. from S. franciscanus Lima & Britsky in River São Francisco (Minas Gerais) closely resembles E. pitalicus, E. coatiarus and E. leporinidis in the lack of a pectinate seta on the first exopodal segment, a feature common in species of Ergasilus in the Neotropics. Ergasilus sinefalcatus n. sp. differs from these species in the presence of a spiniform process on the coxae of legs 2, 3 and 4, an ornament never reported from freshwater species of Ergasilus in South America. PMID:25557749

The Doce River, in southeastern Brazil, is a coastal drainage, configured since the Late Cretaceous, when South America separated from Africa. Of the 77 native fish species of the Doce River Basin, 37 are potentially endangered-Oligosarcus solitarius, Menezes 1987, is the only endemic species of the quaternary lakes in the middle portion of this drainage and Oligosarcus argenteus, Günther 1864, is distributed in the Doce River channel and headwaters. This study characterizes the morphological, cytogenetic, and mitochondrial DNA variation in the Oligosarcus spp. populations from the Doce and São Francisco River Basins. The principal component analysis indicates three morphological groups. Cytogenetic data corroborate existence of the O. solitarius and O. argenteus fish species in the Doce River Basin, with high levels of population cytogenetic polymorphism. Taking into consideration the Pleistocene-Holocene formation of the lacustrine system in the middle Doce River, with low molecular differentiation and high levels of chromosomal variation among the O. solitarius populations, we concluded that O. solitarius has the highest rate of chromosomal evolution observed in Neotropical freshwater fishes. The morphological and cytogenetic patterns of the Oligosarcus sp. population collected at the Das Velhas River headwaters suggest that it may represent an undescribed species. PMID:25602472

A new species of Astyanax from the Rio Paraguaçu basin, Bahia, Brazil, is described. This new species is distinguished from its congeners known to occur in Brazilian drainages by the presence of small bony hooks on all fins of mature males. Furthermore, the new species can be diagnosed by its colour pattern, which consists of a unique vertically elongated humeral blotch, a conspicuous dark drop-shaped horizontal blotch over the caudal peduncle, tapering anteriorly and not extending to the median caudal-fin rays, and by the absence of a conspicuous broad dark midlateral stripe. The new species differs further by having the greatest body depth just anterior to the dorsal-fin origin, 32-35 perforated scales in the lateral line and a reduced number of branched anal-fin rays (16-20). Apparently, the new species does not fit into any species complex of Astyanax. The occurrence of bony hooks on all fins of Astyanax is discussed. PMID:24446730

Moenkhausia lepidura (Kner) is redescribed based on the examination of the type and other specimens from several localities of the Amazon and Orinoco basins. The species is readly diagnosed from congeners by a combination of a dark blotch on the upper caudal-fin lobe, lower lobe hyaline, and by the arrangement of predorsal scales, in which scales of anterior portion of predorsal area are arranged in pairs, followed by a single median row of scales extending to dorsal-fin origin. The analysis of the type material of Gymnotichthys hildae Fernández-Yépez and Knodus calliurus Ahl demonstrated the former is a junior synonym of Moenkhausia lepidura, whereas the latter should be removed from its synonymy. An identification key to the Moenkhausia lepidura-group is provided. PMID:27394824

Two populations of Astyanax altiparanae (Garutti & Britski, 2000) of the Água dos Patos stream/SP and lake Igapó/PR were analyzed. All individuals showed 2n = 50, however, different karyotypic formulae were observed. The population of the Água dos Patos stream showed 8m +24sm+6st+12a (NF=88) and the population of lake Igapó, 8m+28sm+4st+10a (NF=90). Nucleolus organizing regions (AgNORs) were observed in the terminal position on the short and long arm of different chromosomes of both populations, showing a variation from 3 to 4 chromosomes. Fluorescent in situ hybridization (FISH) using 18S rDNA probes revealed only one pair of chromosomes with fluorescent signals in the terminal site on the short arm in the Igapó lake population, while the population of Água dos Patos stream showed 4 fluorescence terminal signals, characterizing a system of simple and multiple NORs, respectively. 5S rDNA fluorescent signals were detected in the interstitial position of a pair of chromosomes in the two studied populations. Some AgNOR sites revealed to be GC-rich when stained with Chromomycin A3 (CMA3), however, AT positive regions were not observed. The data obtained show that, despite the conservation of the diploid number and location of 5S DNAr, differences in both the distribution of 18S rDNA and karyotypic formula among the populations were found, thus corroborating the existing data on chromosome variability in Astyanax altiparanae that can be significant for cytotaxonomy in this group. PMID:24260632

Originally described from the upper Rio das Velhas, a tributary of the Rio São Francisco, state of Minas Gerais, Brazil, Hysteronotus megalostomus was recently collected in many tributaries of the Rio São Francisco north of the type locality. The specimens of the population samples collected outside the type locality share the morphological features present in the type material except for the presence of an adipose fin found only in two specimens within the more recently collected material. Presence or absence of the adipose fin has been extensively used by fish taxonomists to characterize different species and even genera, but in H. megalostomus the character is not consistent, indicating its use alone is not diagnostic. The species is redescribed and its phylogenetic relationships and conservation status are briefly discussed. PMID:27237472

Abstract Karyotypes and chromosomal characteristics of both minor and major rDNAs in four fish species known popularly as “lambaris”, namely Astyanax abramis (Jenyns, 1842), Astyanax asuncionensis Géry, 1972, Astyanax correntinus (Holmberg, 1891) and Astyanax sp. collected from downstream of the Iguassu Falls (Middle Paraná River basin), preservation area of the Iguassu National Park, were analyzed by conventional and molecular protocols. Astyanax abramis had diploid chromosome number 2n=50 (4m+30sm+8st+8a) and single AgNORs (pair 22), Astyanax asuncionensis had 2n=50 (8m+24sm+6st+12a) and single AgNORs (pair 20), Astyanax sp. had 2n=50 (4m+26sm+8st+12a) and single AgNORs (pair 25), and Astyanax correntinus had 2n=36 (12m+16sm+2st+6a) and multiple AgNORs (pairs 12, 15, 16, 17). FISH with 18S rDNA showed a single site for Astyanax abramis, Astyanax asuncionensis and Astyanax sp. and multiple for Astyanax correntinus (14 sites). FISH with 5S rDNA showed single 5S-bearing loci chromosome pair only for Astyanax asuncionensis and multiple for Astyanax abramis (four sites), Astyanax correntinus (five sites) and Astyanax sp. (four sites). Distinct distribution patterns of heterochromatin were observed for karyotypes of all species, with the exception of the first acrocentric chromosome pair characterized by centromeric, interstitial-proximal and telomeric blocks of heterochromatin on the long arm, which may represent homeology between karyotypes of Astyanax abramis and Astyanax asuncionensis. Our study showed species-specific characteristics which can serve in diagnosis and differentiation between Astyanax abramis and Astyanax asuncionensis, considered cryptic species, as well as strengthening the occurrence of a species of Astyanax not yet described taxonomically. In addition, the data obtained from first cytogenetic studies in Astyanax correntinus suggest a high similarity with Astyanax schubarti Britski, 1964, suggesting that these species may belong to the same morphological group and that can be phylogenetically related. PMID:25893074

The penguin tetra (Thayeria boehlkei) is one of the most popular aquarium fish and belongs to the family of Characidae. The composition, phylogeny, and classification of this family are uncertain. Here, the complete mitogenome of T. boehlkei was reported to be 16,524 bp in length. It contains 13 protein-coding genes, 22 transfer RNA genes and 2 ribosomal RNA genes. Comparing the mitochondrial genome of T. boehlkei with its congener Astyanax mexicanus revealed high-sequence similarity. The mitochondrial genome of T. boehlkei will contribute to conservation studies and evolution analysis of Characidae family. PMID:25707407

A new species of the trichomycterid catfish genus Ituglanis is described from the Rio Curuá, Rio Xingu basin, Rio Amazonas drainage, Brazil. Ituglanis apteryx, new species, is promptly distinguished from congeners, except some specimens of I. parahybae (Eigenmann), by the absence of pelvic fins, girdle, and muscles. The new species differs from I. parahybae in the pattern of the cephalic laterosensory system; the absence of a posterior cranial fontanel; the presence of an epural; and the number of branchiostegal rays, ribs, and vertebrae. Ituglanis apteryx is one among the several trichomycterids lacking pelvic fins. Analysis reveals that pelvic fin loss independently evolved several times during the trichomycterid radiation. PMID:24869879

Nematodes of the genus Raphidascaroides Yamaguti, 1941 parasitising doradid catfishes (Siluriformes: Doradidae) in Brazil were studied based on morphological and molecular evaluation of newly collected material. A new species, Raphidascaroides moraveci n. sp., is described from the intestine of Platydoras armatulus (Valenciennes) from River Miranda, River Paraguay basin, Pantanal, Mato Grosso do Sul. The new species differs from all of the congeners in having short spicules (163-217 μm in length) representing less than 1% of the total body length and in the posterior region of cloacal opening covered by small rudimentary spines. In addition, it differs from the other congeneric species in the number and arrangement of the caudal papillae and the structure of lips and tail. Raphidascaroides moraveci n. sp. is the third species described from freshwater fishes and the second one in the Neotropical Region. New morphological data on R. brasiliensis Moravec & Thatcher, 1997 from Megalodoras uranoscopus (Eigenmann & Eigenmann) and Platydoras costatus (Linnaeus) (both new host records) from River Xingu, River Amazon basin, Pará, are provided including scanning electron micrographs of taxonomically important structures. The differentiation of the new species is supported by molecular data (partial sequences of the small and large subunits of the rRNA gene). PMID:25862032

We review the trans-Andean species of Ancistrus from Panama, Colombia and Venezuela. Based on analyses of meristic, morphometric and pigmentation pattern data of preserved specimens, eight of sixteen species reported from this region are considered valid and two new species are described. Here we review Ancistrus chagresi Eigenmann & Eigenmann 1889 from both slopes of central Panama; A. centrolepis Regan 1913 from Pacific slopes of eastern Panama and western Colombia; Ancistrus caucanus Fowler 1943, from the Magdalena River drainage in northern Colombia; Ancistrus martini Schultz 1944, from the Lake Maracaibo Basin of Venezuela and Colombia. Ancistrus galani Pérez & Viloria 1994, from a cave in the Lake Maracaibo Basin of Venezuela is considered valid but was not examined. Ancistrus tolima new species is described from the upper Magdalena River drainage and Ancistrus vericaucanus new species is described from the upper Cauca River drainage. Ancistrus gymnorhynchus Kner 1854 and A. falconensis Taphorn, Armbruster & Rodriguez-O. 2010 were treated previously. One specimen of A. clementinae Rendahl 1937 from the Pacific coast of Ecuador was examined, it is considered a valid species. A key for identification and geographical ranges are provided. PMID:26287090

Oxyropsis ephippia, a new species of loricariid catfish in the subfamily Hypoptopomatinae, is described from the Essequibo and Branco basins, Guyana. Based on the presence of a keel-like row of relatively enlarged odontodes on trunk median plates immediately above the lateral line canal, the new species is assigned to the genus Oxyropsis Eigenmann & Eigenmann 1889. It can be distinguished from its congeners by having the keel-like row on each median plate dominated by a single odontode (one closest to the posterior margin of the plate) conspicuously larger than preceding ones, and by having the sides of the trunk below the median series (approximately between median plates 7 to 12) shielded only by plates of the midventral series, with the exclusion of plates from the ventral series. The report of O. ephippia from the Essequibo is the first record of the genus in a river system that drains the north-central portion of the Guiana Shield into the Atlantic Ocean. PMID:27395707

A new nematode species, Rhabdochona longleyi sp. n. is described from the intestine of two species of blind catfishes, Trogloglanis pattersoni Eigenmann (type host) and Satan eurystomus Hubbs et Bailey (both fam. Ictaluridae, Siluriformes) from the subterranean waters (artesian wells penetrating San Antonio pool of Edwards Aquifer) of Texas, USA. It is characterized largely by the presence of only six anterior teeth in the prostom, simple deirids, by the shape and length of spicules (0.42 to 0.50 mm and 0.093-0.102 mm), shape of the tail tip (rounded), and by filamented eggs. R. longleyi probably adapted to the environment of the aquifer by utilizing available troglobitic crustaceans instead of aquatic insects as an intermediate host. PMID:3198014

Redescription of Parodon caliensis and Saccodon dariensis (Characiformes: Parodontidae). Parodontidae family is a group of Characiformes fishes distributed throughout South America and parts of Panama, except in the basins of the southern Bahia state in Brasil on the Atlantic coast, Patagonia and the Amazon river channel. The family includes three genera: Apareiodon Eigenmann 1916, Parodon Valenciennes 1849 y Saccodon Kner 1863, 28 recognized species and two valid genera: Parodon and Saccodon. Redescription of Parodon caliensis and Saccodon dariensis is carried out based on type, and topotypic material from Colombia. Significant differences were found in morphometric, meristic, osteologic and color characters. S. dariensis is widely distributed but P. caliensis is restricted to the upper Cauca River drainage. Three species are considered herein as synonyms of S. dariensis: Apareiodon dariensis, A. compressus and S. caucae. Sexual dimorphism is described for both species. PMID:20737840

Ecologically, morphologically and genetically distinct populations within single taxa often coexist in postglacial lakes and have provided important model systems with which to investigate ecological and evolutionary processes such as niche partitioning and ecological speciation. Within the Salmonidae, these species complexes have been well studied, particularly within the Coregonus clupeaformis-C. laveratus (lake and European whitefish, respectively) group, but the phenomenon has been less well documented in the other whitefish genera, Prosopium and Stenodus. Here, we examined the morphology, feeding biology and genetic structure of three putative forms of the pygmy whitefish, Prosopium coulterii (Eigenmann & Eigenmann, 1892), first reported from Chignik Lake, south-western Alaska, over 40 years ago. Field collections and morphological analyses resolved a shallow water (< 5 m depth) low gill raker count form (< 15 first arch gill rakers), a deepwater (> 30 m), low gill raker form and a deepwater, high gill raker count (> 15 gill rakers) form. The two low gill raker count forms fed almost exclusively on benthic invertebrates (mostly chironomids), while the deepwater, high gill raker count form fed almost exclusively on zooplankton; differences in diet were also reflected in differences both in δ(13) C and δ(15) N stable isotopes. All three forms were characterized by the same major mitochondrial DNA clade that has been associated with persistence in, and postglacial dispersal from, a Beringian glacial refugium. Analysis of variation at nine microsatellite DNA loci indicated low, but significant differentiation among forms, especially between the two low gill raker count forms and the high gill raker count form. The extent of differentiation along phenotypic (considerable) and genetic (subtle) axes among the Chignik Lake forms is similar to that found among distinct taxa of Prosopium found in pre-glacial Bear Lake (Utah-Idaho, USA) which is probably at least ten

In this work we aimed to characterise the diet of Astyanax taeniatus (Jenyns 1842) (Characiformes, Characidae) along the Mato Grosso stream and we hypothesised that the diet of this species would vary according to spatial, seasonal and ontogenetic differences. Specimens were collected every second month at three sites with different physical attributes. The feeding habits of 651 specimens were analysed using the Alimentary Index (IA(i)). Analysis of the diet showed an effect of spatial, temporal and ontogenetic factors. Vegetal allochthonous items were more important in the diet of Astyanax taeniatus in upstream sites while animal autochthonous items were more important downstream. Ontogenetic differences in the diet were significant only in upstream sites, where adults consumed a greater amount of vegetal matter than juveniles. These results reinforce the idea that Astyanax species are opportunistic and show trophic plasticity. PMID:23295523

During an investigation of the diversity of metazoan parasites of 7 freshwater fish species from 3 localities in central Panama, the following gill dactylogyrid (Monogenoidea) species were found: Aphanoblastella chagresii n. sp. from Pimelodella chagresi (Heptapteridae); Aphanoblastella travassosi (Price, 1938) Kritsky, Mendoza-Franco, and Scholz, 2000 from Rhamdia quelen (Heptapteridae); Diaphorocleidus petrosusi n. sp. from Brycon petrosus (Characidae); Gussevia asota Kritsky, Thatcher, and Boeger, 1989, from Astronotus ocellatus (Cichlidae); Sciadicleithrum panamensis n. sp. from Aequidens coeruleopunctatus (Cichlidae); Urocleidoides flegomai n. sp. from Piabucina panamensis (Lebiasinidae); and Urocleidoides similuncus n. sp. from Poecilia gillii (Poeciliidae). Consideration of the comparative morphology and distribution of these parasites along with the evolutionary history of the host fishes suggests that diversification may be associated with geotectonic events that provided isolation of the Central American fauna with the uplift of the Panamanian Isthmus during early Pliocene (3 mya). PMID:17918354

We present and discuss VARSEDIG, an algorithm which identifies the morphometric features that significantly discriminate two taxa and validates the morphological distinctness between them via a Monte-Carlo test. VARSEDIG is freely available as a function of the RWizard application PlotsR (http://www.ipez.es/RWizard) and as R package on CRAN. The variables selected by VARSEDIG with the overlap method were very similar to those selected by logistic regression and discriminant analysis, but overcomes some shortcomings of these methods. VARSEDIG is, therefore, a good alternative by comparison to current classical classification methods for identifying morphometric features that significantly discriminate a taxon and for validating its morphological distinctness from other taxa. As a demonstration of the potential of VARSEDIG for this purpose, we analyze morphological discrimination among some species of the Neotropical freshwater family Characidae. PMID:27615992

Suprafamilial relationships among characiform fishes and implications for the taxonomy and biogeographic history of the Characiformes were investigated by parsimony analysis of four nuclear and two mitochondrial genes across 124 ingroup and 11 outgroup taxa. Simultaneous analysis of 3660 aligned base pairs from the mitochondrial 16S and cytochrome b genes and the nuclear recombination activating gene (RAG2), seven in absentia (sia), forkhead (fkh), and alpha-tropomyosin (trop) gene loci confirmed the non-monophyly of the African and Neotropical assemblages and corroborated many suprafamilial groups proposed previously on the basis of morphological features. The African distichodontids plus citharinids were strongly supported as a monophyletic Citharinoidei that is the sistergroup to all other characiforms, which form a monophyletic Characoidei composed of two large clades. The first represents an assemblage of both African and Neotropical taxa, wherein a monophyletic African Alestidae is sister to a smaller clade comprised of the Neotropical families Ctenolucidae, Lebiasinidae, and the African Hepsetidae, with that assemblage sister to a strictly Neotropical clade comprised of the Crenuchidae and Erythrinidae. The second clade within the Characoidei is strictly Neotropical and includes all other Characiformes grouped into two well supported major clades. The first, corresponding to a traditional definition of the Characidae, is congruent with some groupings previously supported by morphological evidence. The second clade comprises a monophyletic Anostomoidea that is sister to a clade formed by the families Hemiodontidae, Parodontidae, and Serrasalmidae, with that assemblage, in turn, the sistergroup of the Cynodontidae. Serrasalmidae, traditionally regarded as a subfamily of Characidae, was recovered as the sistergroup of (Anostomoidea (Parodontidae+Hemiodontidae)) and the family Cynodontidae was recovered with strong support as the sistergroup to this assemblage

Abstract Fishes of the Loricariidae family, known as “cascudos”, constitute an endemic group in Neotropical freshwaters. In this study, were cytogenetically examined two species of Loricariidae (Pterygoplichthys anisitsi Eigenmann & Kennedy, 1903 and Farlowella amazonum (Günther, 1864) belonging to Hypostominae and Loricariinae subfamilies respectively) from Iguatemi River. Our study provide the first description regarding C-band and fluorochromic analysis in Farlowella amazonum. In Farlowella amazonum, diploid number was 58 chromosomes, with single Ag-NOR and heterochromatic blocks in centromeric regions of some chromosomes and large subtelomeric blocks were evidenced on the long arm of the pair 27, being this region CMA3+/DAPI-. The Pterygoplichthys anisitsi showed diploid number equal 52 chromosomes, with single Ag-NOR and heterochromatic blocks in centromeric and telomeric regions of some chromosomes and conspicuous large telomeric blocks on the long arm of the pair 10, being this region CMA3+/DAPI-. The results show that karyotype formula is nonconservative in Pterygoplichthys anisitsi and Farlowella amazonum. PMID:25893075

Sharpilosentis peruviensis n. g., n. sp. is described from the catfishes Duopalatinus cf. peruanus Eigenmann & Allen (type-host) and Oxydoras niger (Valenciennes) in the River Amazon basin, Peru. The new species belongs to the subfamily Diplosentinae Tubangui & Masilungan, 1937 of the family Diplosentidae Tubangui & Masilungan, 1937 because of its possession of an unarmed trunk, a cylindrical proboscis, proboscis hooks arranged in longitudinal rows and two tubular cement glands of the same length in males. Sharpilosentis n. g. differs from the other genera of the Diplosentidae in the morphology of the reproductive system: males have a large muscular penis covered with small tubercles and the vulva of females is devoid of muscular sphincters and the cephalic ganglion is located between the second and third part of the proboscis receptacle. In addition, proboscis hooks are of three types: large hooks with simple roots in the anterior part of the proboscis, transitional 6th hook in one from two adjacent rows with bifurcated root in the distal part and small hooks without roots in the posterior part of the proboscis. A partial sequence for the mitochondrial cox1 gene is provided for this new taxon. The taxonomic composition of the family Diplosentidae is discussed. PMID:25962462

Fruit flies were used by several laboratories between 1901 and 1910 for studies of experimental evolution at Harvard, Indiana University, and Cold Spring Harbor before Thomas Hunt Morgan found his white-eyed mutation that we associate with the beginnings of the fly lab at Columbia University. The major players prior to Morgan were William Castle and his students at Harvard University, Frank Lutz at Cold Spring Harbor, and Fernandus Payne whose ideas for working with fruit flies were shaped by his studies of blind cave fauna at Indiana University. Payne's interests were stimulated by the work of Carl Eigenmann, an authority on blind cave fauna, and William Moenkhaus, who introduced Payne to fruit flies at Indiana University before Payne moved to Columbia to pursue graduate work with Morgan and Edmund Wilson. The motivations of the laboratories differed in the theories used for their work. Castle spread the word about the utility of fruit flies for research, but Payne gave Morgan his first fruit flies for research leading to the discovery of the white-eye mutation. PMID:23583801

Pseudoplatystoma corruscans (Spix and Agassiz, 1829) and Pseudoplatystoma reticulatum (Eingenmann and Eigenmann, 1889) are large migratory catfishes of high biological importance and great commercial value in South America. Because fertile crossbreeds can be artificially produced in hatcheries, a high genetic proximity between these two Pimelodidae species is conceivable. Possible escape of crossbred specimens from pisciculture stations is a serious environmental concern. Despite their importance, knowledge of P. corruscans and P. reticulatum biology, ecology, population diversity and genetics is limited. In the present work, the genetic divergence between P. corruscans and P. reticulatum populations from the Paraná River Basin was analyzed on the basis of polymorphisms in ISSR fragments and in the hypervariable sequence of the mitochondrial DNA (mtDNA) control region. Estimates of intraspecific haplotype (h > 0.5) and nucleotide diversities (pi < 0.01) indicate that P. corruscans and P. reticulatum have survived a historical population decline, followed by a demographic expansion. The interspecific polymorphisms within the mtDNA control region and ISSR fragments were suitable as diagnostic molecular markers and could be used to discriminate the two species. A unique Pseudoplatystoma specimen, captured in the Upper Paraná River Floodplain, was identified by these DNA diagnostic markers as a hybrid P. reticulatum x P. corruscans, which possibly escaped from pisciculture. The integrity of the natural population of P. corruscans in the Upper Paraná River is at risk of genetic introgression or homogenization due to the presence of hybrids and the transposition of P. reticulatum upstream through the Canal da Piracema at Itaipu Dam. Data presented herein improve the understanding of the genetic relatedness between P. corruscans and P. reticulatum and represent potential tools for future programs of conservation and surveillance of genetic introgression events and the

The cystidicolid nematode Cystidicoloides fischeri (Travassos, Artigas and Pereira, 1928) is redescribed from specimens collected from the stomach of the San Francisco piranha, Pygocentrus piraya (Cuvier), and the white piranha, Serrasalmus brandtii (Lütken) (both Characidae, Characiformes) (new host records), from the Três Marias Reservoir, Upper São Francisco River, Minas Gerais state, Brazil. The morphology of this type species of Cystidicoloides Skinker, 1931, studied with both light and scanning electron microscopy, is characterized by some taxonomically important, previously unreported features, such as the presence of a cephalic cuticular collarette, subdorsal and subventral cephalic spikes, cuticular tooth-like elevations inside the prostom, deirids, area rugosa, and details in the structure of the cephalic end. Heliconema izecksohni Fabio, 1982 is transferred to Cystidicoloides as C. izecksohni (Fabio, 1982) n. comb. Cystidicoloides uniseriata Valovaya and Valter, 1988 is considered a species inquirenda with uncertain generic appurtenance. The presence of subdorsal and subventral cephalic spikes and the collarette are characteristic of Cystidicoloides, comprising only species parasitizing Neotropical fishes. The species from salmonids in the Holarctic, hitherto reported mostly as Cystidicoloides ephemeridarum (Linstow, 1872), belongs to a different, newly erected genus, for which the name Salmonema n. gen. (type species S. ephemeridarum) is now proposed. Cystidicoloides prevosti (Choquette, 1951) is transferred to Salmonema as S. prevosti (Choquette, 1951) n. comb. Sterliadochona ssavini Skryabin, 1948 and Sterliadochona Skryabin, 1948 are considered as species inquirenda and a genus inquirendum, respectively. A key to species of Cystidicoloides is provided. PMID:18576775

The Pax-6 gene encodes a transcription factor essential for eye development in a wide range of animal phyla. In order to elucidate a possible role of Pax-6 in the eye regression of a blind cave form of the freshwater fish Astyanax fasciatus (Characidae, Teleostei) we investigated the expression of Pax-6 in eyes and brains of different larval stages by in situ hybridization. Pattern, strength, and time course of Pax-6 expression were not altered in the tissues of the cave form when compared to the epigean form. Pax-6 was even expressed in the highly degenerated eyes of late larval stages of the cave form. Comparative sequence analysis of Pax-6 cDNA clones of both forms of Astyanax fasciatus showed the complete integrity of cave fish Pax-6 mRNA. These results suggest that Pax-6 is not involved in the evolutionary process of eye degeneration in this model system of cave-living fishes. Comparison of the Astyanax Pax-6 cDNA with the other available fish Pax-6 sequence from zebrafish revealed putative fish-specific regions of homology. A stretch of 19 N-terminal amino acids is nearly identical on the nucleotide and amino acid levels in both fish species but not present in all other known Pax-6 sequences. PMID:9066797

Background Management and conservation of biodiversity requires adequate species inventories. The Yasuní National Park is one of the most diverse regions on Earth and recent studies of terrestrial vertebrates, based on genetic evidence, have shown high levels of cryptic and undescribed diversity. Few genetic studies have been carried out in freshwater fishes from western Amazonia. Thus, in contrast with terrestrial vertebrates, their content of cryptic diversity remains unknown. In this study, we carried out genetic and morphological analyses on characin fishes at Yasuní National Park, in eastern Ecuador. Our goal was to identify cryptic diversity among one of the most speciose fish families in the Amazon region. This is the first time that genetic evidence has been used to assess the species content of the Napo Basin, one of the richest regions in vertebrate diversity. Results Phylogenetic analyses of partial mitochondrial 16S ribosomal RNA gene (∼600 pb) DNA sequences from 232 specimens of the family Characidae and its closest groups revealed eight candidate new species among 33 species sampled, representing a 24% increase in species number. Analyses of external morphology allowed us to confirm the species status of six of the candidate species. Conclusions Our results show high levels of cryptic diversity in Amazonian characins. If this group is representative of other Amazonian fish, our results would imply that the species richness of the Amazonian ichthyofauna is highly underestimated. Molecular methods are a necessary tool to obtain more realistic inventories of Neotropical freshwater fishes. PMID:26275041

We examined 15 species of ornamental tropical fishes originating from Southeast Asia to determine the cause of losses among 8 fish farms in Korea. A total of 351 individuals belonging to 5 different families (1 species of Characidae, 6 of Cichlidae, 3 of Cyprinidae, 1 of Heleostomatidae, and 4 of Poecilidae) were collected for the purpose of detecting metazoan and protozoan parasites. Parasites were fixed and stained using routine methods, and identified. We found 3 ciliates, 2 monogeneans, 1 nematode, and 1 copepod from 7 host species. Of these, Ichthyophthirius multifiliis was the most common parasite in our study, and together with Trichodina sp., caused mass mortality of Sumatra barb Puntius tetrazona at 1 farm. We also found Camallanus cotti and Tetrahymena corlissi from guppies Poecilia reticulata, both for the first time in Korea. Farmers consider these 2 pathogens to be the most serious ones in Korea. Gussevia asota from oscar Astronotus ocellatus, and Gyrodactylus bullatarudis from platy Xiphophorus maculatus were also found in Korea for the first time. We believe that appropriate quarantine practices for tropical ornamental fishes should be introduced because the failure to require and implement quarantines has already resulted in the accidental introduction of exotic parasites to fish farms, and because these parasites can cause further economic losses if they become established in the wild. PMID:12542094

We compare the classic model of feeding of tropical fish by means of six bimonthly samplings using gillnets of varying mesh sizes that were inspected every twelve hours throughout a forty-eight hour period. The stomachs of the fish caught were classified in three categories according to quantity of food found. The amount of fat in the visceral cavity with respect to the energetic reserve deposition was also studied. The relative frequencies of the different categories of stomach repletion and fat deposition were examined for patterns of feeding seasonality. The stomachs considered full were examined to record diet composition. To assess the relative importance of the different food resources, we applied Feeding Importance Degree (FID), which is a useful index when difficulties exist in determining a common basis for volume, number, or weight of a given food item in different species, a common problem when dealing with fish species having different feeding habits. The fish species whose stomach contents were analyzed using the FID index were Serrasalmus spilopleura (Characidae), L. prolixa (Loricaridae), Schizodon nasutus (Anostomidae), and Pimelodus maculatus (Pimelodidae). Our findings indicate some contrasting elements, in dietary composition in relation to the classic model for tropical rivers. These factors include the importance of aquatic macrophytes, the lack of piscivorous species, and a lesser presence of allochthonous vegetation in the diet of the species studied. PMID:16341415

The growth of sibling dorada Brycon moorei (Characidae) housed individually in small enclosures (0·25 l; 27·0° C, range ±0·5° C; 12L:12D) from the egg stage was examined at regular intervals until 36 days after hatching (dah) and compared with their behaviour. From 1 to 8 dah, when cannibalism is intense among B. moorei raised in groups, there was no significant increase of size heterogeneity among isolated fish (c.v. of total length of 3·1 and 3·6%, at 1 and 8 dah, respectively) and no primacy of early size differences either. These results suggest that cannibals of B. moorei raised in groups are not natural-born killers with greater growth capacities than others. Size heterogeneity among isolated fish increased significantly first when B. moorei were weaned on formulated feed (8-15 dah), then again from 24 to 36 dah when the average growth rate was half as fast as before (c. 0·5 v. 1·0 mm day(-1) ), despite fish consistently feeding. During both periods, there was a significant, positive relationship between individual growth and aggression or boldness. These results suggest that (1) boldness can favour the transition to a new food type and (2) fish exhibited a variable responsiveness to spatial restriction in small enclosures, which may have been alleviated in some individuals by establishment of territorial behaviour, as suggested by their enhanced aggression. PMID:20840625

The Itupararanga Reservoir is located at the Sorocaba River Basin, São Paulo State, Brazil. Five cities use the waters of this reservoir for human consumption. Despite this intensive use of the water resource, no study has been undertaken on the ichthyofauna of this reservoir. Collections were performed in nine sampling stations, where each three were located in the riverine, transitional and lacustrine zones. Fish specimens were collected using eight monofilament gillnets of 10 m length each, with varied mesh sizes, in the rainy and dry seasons, which corresponded to our spatial scale of analysis. Overall, 14 species of fish were identified, with the highest contribution from Characidae and Curimatidae. The most abundant species were: the "lambari", Astyanax fasciatus, the "saguiru", Cyphocharax modestus, the "lambari bocarra", Oligosarcus paranaensis, and the "mandi", Iheringichthys labrosus. Diversity tended to be higher during the dry season, although the difference was not statistically significant. Cluster analysis identified four season sampling groups differentiated by within-season distribution of species. Mantel's test showed that this distribution was little affected by environmental factors, suggesting that biotic factors were more important in determining the species distribution within the reservoir. PMID:19419097

The present study was based on the analysis of spraints (n = 294) collected between December 2005 and November 2007. The importance of each type of prey was determined by absolute and relative frequency. Niche breadth was also estimated. The results were reported as mean (± SD) of relative frequencies. Fish were the main prey found in spraints (57.8 ± 7.0%). Fish from Callichthyidae family were the main prey, followed by Cichlidae, the species Hoplias malabaricus and the family Characidae. The frequencies of other fish and taxa were lower than 13.9% (absolute frequency) and 5.6% (relative frequency). Despite significant seasonal variations, (P = 0.001), niche breadth values were low in all seasons (0.39 ± 0.11). Therefore, Lontra longicaudis presented a narrow niche breadth as a result of consistent fish predation. Based on these data, fish with rapid movement presenting territorial behavior and benthic fish with slow movements are the most consumed. Seasonal fluctuations are caused by the increase of secondary prey in the diet during some seasons. PMID:23460432

Oligosarcus jenynsii and Oligosarcus robustus are fishes of Characidae family that occur in Rio Grande do Sul, Uruguay and northern Argentina. This work purported to study the feeding dynamics (repletion and hepatosomatic indexes and condition factor) over time, and to investigate the coexistence of these two species by evaluating the partition of resources using qualitative and quantitative analyses of diet, temporal and spatial segregation throughout the water column and some ecomorphological aspects of the species in the Lagoa Fortaleza. Specimens were sampled monthly, from May 2000 to April 2001 during 24 h/month, using stationary gill nets of different mesh sizes. The records of each individual included total and standard length; total, stomach and liver weight; sex and stomach repletion. The variation of the mean values of repletion index and relative frequencies of stomach repletion stages indicate that O. jenynsii and O. robustus do not present seasonal differences in feeding intensity. The hepatosomatic index shows an allocation of energy to the liver during every period except reproduction, when part of the energy is used for gonad maturation. The estimated condition factor for both species reveals an increase in the reproductive period, evidencing the influence of gonads upon the condition of the fish. The diet analysis revealed that O. robustus is piscivorous, whereas O. jenynsii is a generalist carnivore, tending to piscivory as well. The active period of O. robustus is more concentrated at sunrise and sunset, whereas O. jenynsii is continually active, a characteristic related to hunting for prey. The ecomorphological analysis revealed differences between the two species in the dimensions of the mouth. Evidence suggests that the species coexist, sharing food sources, differing in oral morphology but ingesting similar prey, possibly because food is not a limiting factor in the environment. PMID:16680315

In Costa Rica, thousands of tones of agricultural pesticides have been used for decades and their use is continuously increasing due to intensive and expanding production of coffee, pineapple, rice, ornamental plants and bananas. The objective of this study was to evaluate whether choline esterase (ChE) activity could be used as a biomarker of exposure to pesticides in the Costa Rican native fish Astyanax aeneus (characidae). Three methods used in order to evaluate the ChE biomarker were as follows: Laboratory studies where A. aeneus was exposed to organophosphate pesticide (ethoprophos); In situ 48 hr exposure assessment using caging experiments with fish exposed upstream and downstream of banana plantations and ChE activity estimation of in fish captured directly at sites with different degrees of pesticide exposure. Results from the laboratory studies showed that ChE activity in both brain and muscle tissue was significantly lower in fish exposed to ethoprophos than in controls. Fish from the caging experiments showed no difference in ChE activity neither in brain nor in muscle tissue between the four tested sites and was attributed to the short duration of the exposure. Asignificant difference in ChE activity was determined in muscle of fish captured from Laguna Madre de Dios compared to fish from Canal Batán. Although our laboratory results revealed that ChE activity in A. aeneus was highly responsive to ethoprophos, results from field experiments were less conclusive and showed that the captured fish showed large variability in ChE activity and that more research is needed before ChE activity can be used as reliable biomarker of pesticide exposure. PMID:24579519

We evaluated the relationship between limnetic characteristics and fish community structure (based on species richness, abundance and individual size) in contrasting but interconnected inland aquatic habitats of freshwater karstic wetlands in the Yucatan peninsula, Mexico. In the western hemisphere, freshwater karstic wetlands are found in south-eastern Mexico, northern Belize, western Cuba, Andros Island, Bahamas and the Everglades of southern Florida. Only in the Everglades have fish communities been well described. Karstic wetlands are typically oligotrophic because calcium carbonate binds phosphorus, making it relatively unavailable for plants. Fourteen permanent and seasonally flooded water bodies were sampled in both wet and dry seasons in Sian Ka'an Biosphere Reserve, in the Mexican state of Quintana Roo. Water systems were divided by morphology in four groups: cenotes with vegetation (CWV), cenotes without vegetation (CNV), wetlands (WTL), and temporal cenotes (TPC). Discriminant analysis based on physical characteristics such as turbidity, temperature, depth and oxygen confirmed that these habitats differed in characteristics known to influence fish communities. A sample-based rarefaction test showed that species richness was significantly different between water systems groups, showing that WTL and CWV had higher richness values than CNV and TPC. The most abundant fish families, Poeciliidae, Cichlidae and Characidae, differed significantly in average size among habitats and seasons. Seasonal and inter-annual variation, reflecting temporal variation in rainfall, strongly influenced the environmental differences between shallow and deep habitats, which could be linked to fish size and life cycles. Five new records of species were found for the reserve, and one new record for Quintana Roo state. ?? 2006 by Verlag Dr. Friedrich Pfeil.

The Kpong Headpond was the second created on the Volta River after Akosombo Dam, primarily as a source of hydroelectric power generation and potable water supply, and additionally, it has supported some fish production in Ghana since impoundment. The changes in fish community of the Kpong Headpond were studied to provide baseline information for strategies formulation to support the socio-economic development of the reservoir. The study identified changes in the fish community of the reservoir by comparing occurrence, composition, relative abundance and relative importance estimates of fish species, families and trophic groups, from available previous studies in the reservoir. From the collated information all fishes identified in the reservoir were categorised based on occurrence and importance as disappeared, appeared, permanent, declined or important, to show current status. The results indicated that the fish community has experienced a shift in the composition and relative abundance of important species, families and trophic groups in terms of number and weight, while remaining ecologically balanced. Representatives of the families Osteoglossidae, Centropomidae and Characidae have declined while representatives of the families Claroteidae, Cyprinidae and Cichlidae have increased. The aufwuch-detritus and herbivores declined while semi-pelagic omnivores increased resulting in a shift in dominance to benthic and semi pelagic omnivores. The appearance of five species and the disappearance of 25 others indicated a dynamic restructuring of the fish community in the reservoir, as expected. Enforcement of fishing regulations including the use of appropriate gear and fishing methods, fishery access control, promotion of culture-based fisheries and improvement in fisher education are recommended topics for sustainable fisheries in the reservoir. PMID:22208085

The fish yields of most Nigeria inland waters are generally on the decline for causes that may range from inadequate management of the fisheries to degradation of the water bodies. Sustainable exploitation requires knowledge of the ichthyofaunal composition in the water bodies. We did a survey of fish species in Anambra river basin for 22 months. Fish samples were collected using four different gears -hook and line of size 13, caste nets, gill nets, and cages of mesh sizes of 50 mm, 75 mm, and 100 mm each. We recorded 52 fish species belonging to 17 families: 171, 236, and 169 individuals at Ogurugu, Otuocha, and Nsugbe stations respectively. Two families, Characidae, 19.5%, and Mochokidae, 11.8%, constituted the dominant fish families in the river. The dominant fish species were Citherinus citherius, 9.02%, and Alestes nurse, 7.1%. Other fish species with significant abundance were Synodontis clarias 6.9%, Macrolepidotus curvier 5.7%, Labeo coubie 5.4%, Distichodus rostrtus 4.9%, and Schilbe mystus 4.5%. The meristic features of the two most abundant fish species caught are as follows: Citharinus citharius dorsal fins 20, anal fins 30, caudal fins 21, pectoral fins, 9 and 8 ventral fins, and Alestes nurse 10 dorsal fins, 14 anal fins, 31 caudal fins, 7 pectoral fins and 6 ventral fins. The morphometric features of the two most abundant fish species are Citharinus citharius total length 300 mm, standard length 231 mm, head length 69 mm, body length 101 mm, body girth 176 mm, body weight 900 mg. Alestes nurse total length 200, standard length 140 mm, head length 60 mm, body length 80 mm, body girth 120 mm, body weight 400 mg. The most abundant animal utilizing the basin was Ardea cinerea (D3) with 22.2% occurrence (D4) and this was followed by Caprini with 13.51%, and Varanus niloticus, 10.04%. The least abundant animals utilizing basin were Chephalophus rufilatus, and Erythrocebus patas, with 0.58% each of occurrence. PMID:19637699